# Setting up coldwater tank



## wind1

Having just lost the last of my goldfish I would like to now use the tank for some small coldwater fish. Just need some advice please on cleaning out the tank, refilling it and what are the best small coldwater fish to get and how many. My tank is 90 litres and will have a light but not a heater. I would like the easiest, hardiest fish but not goldfish again.


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## NaomiM

What did the goldfish die of? If it was anything infectious such as whitespot, it's worth using bleach to clean out the tank (just be sure to rinse, rinse and rinse again!) and chuck out the substrate, filter media and decor.

I'd highly recommend doing a fishless cycle before you get any new fish - it's the most humane way to set up a tank and gives you the best possible chances of success with the minimum stress - just a bit of patience needed! Here's a link if you need more info: http://www.tropicalfishforums.co.uk/index.php?page=setting up your new aquarium

In terms of fish, white cloud mountain minnows are the only true coldwater fish I'd recommend for your tank - they're very hardy and attractive and come in a gold variety as well as the wild-type silver and red colouration. If the tank's in a room that's well heated during the colder months and the room temp isn't likely to drop lower than 18 C, then you have a few more options such as gold or odessa barbs, variatus platys, American flagfish, and certain types of tetra (can't remember which ones right now, I'll have to look it up!) I have WCMMs, odessa barbs and American flagfish in my coldwater tank, and they're all pretty easy fish to care for, though I've occasionally heard of American flags bullying other fish if they don't have a constant food source (they like to graze on algae and/or floating plants).

Hope this helps!


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## wind1

Thank you, that's a great help


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## wind1

My tank has been set up for 5 weeks now. I had it up and running for 3 weeks then added 5 zebra danio's, then the following week 5 WCMM's. I am looking to add more next week. I have been looking online at red cherry shrimp. Would they be suitable for me, I want something that uses the bottom of the tank as the danio's and minnows spend most of their time between the middle and the top. I would also like a couple of apple snails but the fish shop said they are hard to get hold of. He also said to wait a couple of months before putting any snails in to give the bacteria time to build up. Any recommendations for bottom dwellers and where I could get snails when I want them?


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## NaomiM

Please don't add any more fish just yet, as your tank will not be cycled. Leaving it to 'stand' for three weeks is not cycling it - it's just a piece of completely pointless advice that pet shops give out sometimes for some reason. Unless you were adding a controlled source of ammonia during those three weeks and testing the water daily, it would have had no effect whatsoever.

You're now doing a 'fish in cycle', which is the old-fashioned way of setting up a tank, and may unfortunately cost you some of your fish. To minimise the chance of this happening, you need to get hold of a liquid test kit such as the API master kit, and test your water daily for ammonia and nitrite. Any time the levels are above 0.25 for either of these toxins, do a 50% water change. (This may be daily.) Your tank is not cycled until you have been getting readings of 0 for both ammonia and nitrite for around 4 consecutive days. PLEASE DO NOT ADD ANY MORE FISH OR OTHER LIVESTOCK until you reach this stage, or the levels of toxins will rise even more quickly, poisoning your fish. Even if it doesn't kill them, it will shorten their lifespans and make them susceptible to other problems such as infections.

When your tank is fully cycled, you could look into peppered corys or panda corys as possible bottom dwellers, but all bottom dwellers are particularly vulnerable to ammonia and nitrite poisoning, as the water quality tends to be worse the lower down you go.

Apple snails are now illegal to import due to their invasive nature, so many shops have stopped stocking them. It's not illegal to keep or breed them, so it's possible you may find a shop or a private seller who has some, but again, please make sure your tank is fully cycled first! Red cherry shrimps I believe like slightly warmer temps, so may not be suitable for a coldwater tank.


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## wind1

Thanks, I had the water checked at the fish shop after the 3 weeks, and again a week later. They told me it was ok to add the fish but I guess they would because they want to sell some fish! I felt they were very knowledgeable and trusted they would tell me what was best for my tank otherwise surely if fish started to die people would be going back and complaining. I certainly will be if any of mine die. I will go to the pet shop tomorrow and get a test kit then go from there. I won't be adding anything else until I know it's safe to do so. Thanks again for your advice.


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## NaomiM

Unfortunately most shops are only in it to make money, as you say. I learnt the hard way that it's generally better to rely on advice from hobbyist forums, where people have no motive other than the fish's welfare!

By the way, don't let them sell you the paper test strips - they're pretty much a waste of time as they're inaccurate. A liquid drop test kit will be more expensive, but it's a worthwhile investment as it will last you a good couple of years and will be your first point of reference if you have any problems in your tank.


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## wind1

Ok, so finally got hold of the liquid test kit (pet shop in my town did not have them, only strip tests). I'm measuring the levels now. Ammonia I would say is between 0 and 0.25 but closer to 0.25, and the nitrite is 0. Have also tested nitrate, that is 40, and pH is 7.6


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## NaomiM

Not too bad  Just keep a close eye on it, test it every day, and do a water change any time ammonia or nitrite rises above 0.25 (and no less frequently than once a week).

It's also worth testing your tap water for nitrate, as in some areas it comes out of the tap at 40ppm, which obviously means that water changes won't be able to get it any lower! Most fish are fine with 40ppm nitrate, though, so it's not an issue unless it rises to 80 or so


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## wind1

If it stays low am I ok to add more fish, I was hoping to put the next 5 in on Sunday. When I do a water change I have been doing 10%, is that ok?

Have just looked back at your previous reply and you've said to wait until readings are 0 for 4 days in a row. I will test over the next few days and see if the ammonia reading comes down.


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## NaomiM

I'd be very surprised if your tank is cycled after only a couple of weeks (not including the 3 weeks it was sat doing nothing); it normally takes much longer than that. So yes, keep testing daily, and don't add anything else yet. You may not even have reached the nitrite stage of the cycle yet, which is just as dangerous to the fish as the ammonia stage.

Water changes in a fully cycled tank should be 20-25% weekly. If your ammonia or nitrite rises above 0.25%, you need a bigger water change to bring it back down to under 0.25. So, for example, if you have a reading of 0.5, you need to do a 50% water change. If you have a reading of 1.0, you'll need to do TWO 50% water changes in the same day.


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## wind1

So even though the levels are low at the moment they could well go up? What would make them go up now when the fish that are in there have been in for 2 weeks. Sorry for so many questions but having had goldfish for the last 14 years and going by what the pet shops have been telling me, I'm now learning lots of new and different things (which can only be a good thing for me and the fish!)


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## NaomiM

No probs, more than happy to answer any questions I can  Basically ammonia is produced as fish waste and leftover food decompose, so the ammonia levels will gradually build up until enough filter bacteria develop to be able to cope with them. These bacteria turn the ammonia into nitrite at a ratio of around 1:4, so ammonia at 0.25ppm will become around 1ppm of nitrite; 1ppm of ammonia would become 4ppm of nitrite, and so on. Then another different type of filter bacteria turns the nitrite into harmless nitrate; but this bacteria doesn't normally develop until later on, so you could well see a large nitrite spike first.

Hope this makes sense!


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## wind1

Thank you, yes it does make sense but I do have some more questions! How does the bacteria grow in the filter (sounds like a silly question now I've written it down)? And how long do you think it will take for the nitrite to spike if it does? Also I had algae building up on the glass front of the tank at the bottom where the gravel is, I have cleaned it today and done a water change. Was this the right thing to do?


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## NaomiM

Not a silly question at all  Bacteria will eventually grow in the filter by itself, but the process will be greatly speeded up if you can get hold of a little bit of mature media, or even a squeeze of water from a filter sponge, from a fishkeeping friend, and put this in your filter to start the colony off. (Bear in mind it should be out of the filter for the minimum possible time while transferring it, ideally less than 30 mins, and don't let chlorinated water touch it at any point as this will kill the bacteria.)

Another option is to add some 'bottled bacteria' such as Filterstart, though the jury's still out as to how effective these are!

Once the first bacteria are in the filter, they will multiply faster or slower depending on the conditions - warmer temperatures will make them multiply faster, but the species you have in your tank won't like it too warm, so you're at a disadvantage there. The first stage of the cycle can take anything from a couple of weeks to several months, depending on tank conditions and whether or not you have some starter bacteria - so in your case, it could well be two months or more, unless you manage to get hold of some mature media from somewhere to give it a 'kick start'.

Re the algae, a brownish type of algae on the glass (known as diatoms) is very common in new setups (and is still plaguing my coldwater tank after 6 months!) Scrubbing it off and hoovering it up with a gravel syphon is fine; if you have no live plants, you could also try leaving your tank lights off to stop it spreading so fast.


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## wind1

Fish tank has been up and running for 5 weeks now with fish in. Water readings are still at 0 for ammonia and nitrite and have been each time I've tested which has been every other day up until Tues then every day to today. Would it be ok for me to add more fish yet, I'm getting impatient now! I have ordered some filter start which should be here today or tomorrow. Should I wait until I have put some of that in before adding more fish?


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## NaomiM

It's possible it's cycled already (if you were testing every other day, you may have missed a small nitrite spike, as this stage can happen quite suddenly!) in which case you've been lucky to have a nice quick cycle! To be on the safe side, since you've already ordered Filter Start, I'd give it a try with that first, and wait 3-4 days (testing daily) to see if you get nitrite readings (keep testing for ammonia as well).

How frequently have you been doing water changes? If you haven't done one in a few days, try testing a sample of tank water for nitrAte, and compare this to a sample of your tap water. Unless you have live plants in your tank (which would reduce the nitrate), the tank water should have higher nitrates than the tap water if the filter bacteria have been doing their job properly.

Which fish are you planning on adding? Corys are more sensitive and live near the bottom of the tank where the water quality is worst, so it's generally advised to wait several months even after the cycle is complete before adding corys. If you were planning to boost your shoals of WCMMs or danios, though, you may be OK to add a couple more in a few days' time so long as everything continues to indicate that your tank is cycled.


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## wind1

Water change weekly, did last one last Sunday. I don't have any live plants in the tank, I will test nitrate tomorrow. I was hoping to add 5 leopard danios or another 5 WCMMs. So hopefully the filter start will arrive in the next couple of days, then I'll test the water throughout next week and all being well add some fish next weekend, fingers crossed. I'm loving watching my little fish, having only ever had goldfish I never realised how interesting and watchable these little ones could be. Thanks again for all your advice.


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## wind1

Another question, you mention Corys, would they be suitable for my tank? They look interesting and I would love to have some, have been looking online at the different types and would like the smallest which seem to be Panda Corys. They say they should be kept in groups, would 90lt be suitable for a group and if so how many?


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## wind1

Have tested nitrate. Tank water is 40, tap water is 20. I'm guessing those readings are good? Managed to drop and break one of the test tubes in the process, then forgot which was tap water and which was tank so had to start all over again!! This fish keeping lark is not easy is it?!


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## NaomiM

Those test results are good as they show that the fish waste is being processed  The nitrate is produced when the filter bacteria digest nitrite, which in turn is produced when other filter bacteria digest ammonia. Nitrate up to 40ppm is not harmful to most fish, but do check every now and then to make sure it's not rising too far above this - with no live plants, you may need to slightly increase the amount of water you change each week to stop it building up too much, especially once you're fully stocked 

Re corys, so long as the tank is in a heated room and never drops below 18 C or so, there are several species of corys that will thrive at room temperature, two of the most popular being panda corys and peppered corys. Any species of cory should be kept in groups of 5+, and a 90l tank will be fine for this number. My personal experience with pandas is that they're quite sensitive and prone to problems, so I've given up trying to keep them - but that may well be because I have hard water with pH of 8, and they really prefer soft, acidic water. I may well end up with some peppered corys in my coldwater tank, though, as they are one of the hardiest species 

It's well worth having a play with aqadvisor.com to help you decide on your final stocking and how many of each species, once you have a general idea of what you want in your finished tank


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## ameliajane

The best success I've ever had with cory cats was in a 60L (2' long) tank that had a very fast running filter with a venturi valve that aerated the water. 
The tank held a group of White Cloud Mountain Minnows and a group of Panda Corydoras. 

The Panda cats bred like rabbits!


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## wind1

Have put desired fish into aqadvisor and it comes out at stocking level 100% so I'm happy with that, I can have the fish I want eventually.


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## wind1

ameliajane said:


> The best success I've ever had with cory cats was in a 60L (2' long) tank that had a very fast running filter with a venturi valve that aerated the water.
> The tank held a group of White Cloud Mountain Minnows and a group of Panda Corydoras.
> 
> *The Panda cats bred like rabbits*!


Not sure I want them breeding, what do you do with them all? Do the fish shops take them? Think I might go with peppered corys if they're a bit hardier.


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## DarrenH

_*I have a filtered, tropical tank so it may not apply to you. Still, some tips in case you aren't aware/unsure/maybe future reference.*_

I've recently set up a tank I bought from someone on gumtree. Full set-up minus gravel and the filter needed to be replaced. Cleaning wise, I just used washing-up liquid and gave it several thorough washes to make sure there was no liquid left in it.

As people have mentioned - don't put in any fish for a good two to four weeks (no less than two). I made that mistake and my tank went very cloudy, green and stank. Fortunately they were hardy fish and there was no repercussions.

I don't know if it has been mentioned too but don't clean your filter. Don't wash the sponges. The existing bacteria in your filter will speed up the cycle. If not, your tank will play catch up.

People also advise 10% water changes every week.

May help, may not. Hope you enjoy your new set-up!


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## ameliajane

I had a large tank that they could be moved in to and I gave them to friends too. 
They never did particularly well in the larger, deeper tanks and they certainly never bred. 
They do seem to appreciate shallower, cooler, very well oxygenated water.
I don't know whether shops would take them off your hands if they were to breed.
I suppose you could always advertise them for sale or to a good home.


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## wind1

DarrenH said:


> _*I have a filtered, tropical tank so it may not apply to you. Still, some tips in case you aren't aware/unsure/maybe future reference.*_
> 
> I've recently set up a tank I bought from someone on gumtree. Full set-up minus gravel and the filter needed to be replaced. Cleaning wise, I just used washing-up liquid and gave it several thorough washes to make sure there was no liquid left in it.
> 
> As people have mentioned - don't put in any fish for a good two to four weeks (no less than two). I made that mistake and my tank went very cloudy, green and stank. Fortunately they were hardy fish and there was no repercussions.
> 
> I don't know if it has been mentioned too but don't clean your filter. Don't wash the sponges. The existing bacteria in your filter will speed up the cycle. If not, your tank will play catch up.
> 
> People also advise 10% water changes every week.
> 
> May help, may not. Hope you enjoy your new set-up!


Thank you, I am now 5 weeks in and have some fish in already. I am very much enjoying them and will be adding more soon.


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## NaomiM

It's definitely worth testing your water's pH, and looking at your water company's website to get a general idea of hardness. Highly unlikely your corys will breed if your water is like mine - but a decent chance of it if you have soft, acidic water  They like to lay their eggs in bushy plants, though I believe they will also use artificial plants if you have the type with lots of small, clustered leaves or fronds. If you are lucky enough to have them breed, I'm sure you won't have too many problems finding homes for the babies - just advertise them on a few fish forums, corys are always popular and you may make some money out of it too  As ameliajane says, they like lots of water movement and flow, and your minnows and danios will also appreciate this. Airstones are apparently good too, as they like to play in the bubbles


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## DarrenH

wind1 said:


> Thank you, I am now 5 weeks in and have some fish in already. I am very much enjoying them and will be adding more soon.


Glad it's going great!

In regards to the worry about breeding. What about gumtree? Fish tanks are so common these days, fish die. There's always someone looking for more. You could make a little bit of money out of chance. The guy I got my tank from has fish that constantly breed. I told him that if he has any in the future to let me know.


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## wind1

I have now added another 5 WCMM, I made a bit of a mistake with choosing them, not realising they were the same as the five I already had! They looked different in the shop so I now have 10 WCMM's and 5 zebra Danio's. I don't mind the WCMM's being all the same but it would have been nice to have a different variety. Also all the WCMM's spend nearly all their time at the top of the tank so you don't see them very much. I will definitely be looking to add some corys otherwise my tank will look empty apart from a few danio's. So, added the new fish on Thurs, then yesterday the Filter Start arrived so I added some of that. This morning I have tested the water, ammonia and nitrite still at 0 but nitrate has gone up. It's up to at least 40, it's quite hard to tell as the colour on the chart between 40 and 80 are quite similar. Would the filter start affect the rise in nitrate? I will do a water change now and test again later. Also with the feeding I really don't know if I am feeding them the right amount. I feed flake food and on the tub it says to feed 2 or 3 times daily but this seems a lot so I only feed once. I have no idea though if I am feeding enough, I'm worried to feed too much as I don't want the waste to build up. How do you know how much is the right amount. The amount I feed gets eaten within about one minute.


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## NaomiM

Re the nitrate, I wouldn't worry too much about it - like I said, it's a good sign that the filter's working correctly. You should be changing around 20-30% of the water every week, which will keep it under control, but if it's looking a little high, adding in an extra water change or two will help to reduce it. Now that your tank's cycled, you could also reduce nitrates by a gentle clean of SOME (but not all) of your filter media once a month or so - do this by gently swishing it in a bucket of old tank water when you do a water change. Never clean all your filter media at once as you'll lose too many good bacteria, and NEVER let it come into contact with tap water, as the chlorine will wipe out your bacteria colony.

It sounds like you're feeding just the right amount - don't increase feeds as this will increase your nitrate! Your fish will appreciate some variety, though,and some high quality protein, so it's worth replacing the flake with some (defrosted) frozen food once or twice a week. You can buy this in frozen blister packs in most fish stores - just pop out one blister into a jug of tank water and let it defrost before pouring it in. Good choices include bloodworm, daphnia and brine shrimp. Corys in particular need plenty of protein - I give mine frozen food twice a week, and a high-protein sinking pellet on the other days (fed along with the flake).

Another useful addition to the diet in a community tank is to feed a defrosted, shelled and crushed pea once a week instead of the flake - this has a laxative effect and helps keep their digestive systems working effectively.

Sounds like all's going well in your tank - I think we need some pics please! :-D


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## wind1

Ok thanks, I was going to ask about other food for them so will get some of what you suggest. I have solved the problem of the WCMM's being at the top of the tank all the time. The filter I have has an output spout at the top and bottom and a spray bar. I had it set on the top so I've changed it to the spray bar and they immediately started swimming around lower down so now I can see them without having to crouch down all the time! Here's a couple of pics. Most of them are at the top because as soon as I get close to the tank they seem to all go to the top, I guess it's because they think they will get fed.

















Excuse the attached tortoise picture, I attached it by mistake and can't get rid of it?!


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## ameliajane

Sounds like you're doing great and you have lovely fish!
White clouds are far more interesting than they first seem. They are really quite colourful once they mature and they display to each other by swimming side by side and fluttering their fins very fast. If they're given a fast flowing filter they love to play in the stream and the air bubbles. 
One of my favourite fish!
(Tortoise is very cute too!)


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## wind1

Would an air stone be worth putting in? I have looked at some but not sure if it would be beneficial. Also not completely sure how it runs? Is it something you plug in or does it fit to the filter somehow?


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## NaomiM

Looking good  I love WCMMs too - the adult males have a bright yellow colouration to the tips of their fins, which looks stunning when they display to one another!

An airstone is more for decoration than for any particular benefit it adds to the water (aeration happens at the surface, so the bubbles aren't adding any oxygen to the water), but WCMMs and corys do enjoy playing in the bubbles, so it's really up to you 

One note on your current set-up - if you do decide to go for corys, I'd highly recommend switching to sand instead of gravel. Gravel wears down their barbels (the little whisker-like feelers around their mouths which they use to find food), opening them up to the risk of infection and also making it harder for them to get all the food they need. Plus sand is easier to keep clean, as gravel tends to get fragments of food and waste caught between the stones. Switching to sand is quite a time-consuming and fiddly task, but well worth it IMO - feel free to ask for advice if you need it


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## wind1

Time consuming and fiddly sound unattractive to me at the moment so think I might give the corys a miss for now. Now the WCMM's are using more of the tank to swim around I'm not so bothered about having something that uses the bottom. I'll probably go back to my original plan and get a couple of Apple snails eventually. Before that I will be adding 5 Leopard Danio's, not yet, I'll let the others settle first. Thanks again for all the advice. Tomorrow I will probably be out looking for an airstone and some frozen food. Oh, one more question, when I clean the filter media should I take out the carbon filter? I have read somewhere it is not necessary to keep it in the filter. Is that right?


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## wind1

Ok, I knew it was all going too smoothly. I seem to have lost one WCMM. I can only count 9, cannot see the tenth one anywhere. The only place it could be is under one of the ornaments so I guess I need to get them out and have a look. Unless the others or the danios have eaten one, would they do that? Also another WCMM is acting oddly, it is just staying in the same spot, not swimming around and its tail fin is droopy. I tested the water last night and all ok there, ammonia and nitrite are still 0 and nitrate 40. I have googled droopy fin and found it could be a symptom of low pH so I'm going to test that now.

Update: Tested pH, that is at 7.6 so hasn't changed. I lifted the 2 ornaments and although I didn't see a fish swim out I now have 10 again so I'm guessing one was hiding. There are now 2 though with drooping tail fins. Just to recap what has happened in the tank over the last few days. Thursday introduced 5 new WCMM's, Friday added some filter start, Sunday 10% water change (had done a 10% on the Tues before as well), Sunday fed them a frozen block of Daphnia (defrosted it first in tank water). Any ideas please?


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## NaomiM

Not sure about the drooping tail fins. Has it improved or worsened at all since your last post? Any other symptoms at all? Were the tank lights off at the time, could they just have been sleeping?

Re the minnow hiding, my fish (all species) do that all the time, little so-and-sos!


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## wind1

One of them now has a ragged tail fin. ameliajane has very kindly been giving me advice as I was worried it could be fin rot. She suggested it could be fungus in which case I need to treat it quickly. The tank lights were off, they are now on and one has gone into hiding again. The other is just staying in the same place with his ragged droopy tail.


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## ameliajane

If you can't actually see any fungus hold off any treatment for now and do large daily water changes. 
Monitor the tail to see whether it gets any worse.


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## NaomiM

I agree with ameliajane, though if you have some melafix, this can help prevent infection and won't interfere with any future treatments needed. It could be that they're being picked on - although it's rare to see them at it, danios can sometimes be a bit stroppy and bully the other fish a bit, especially if your shoal of danios is quite small (in a larger shoal, they tend to show off to each other rather than bothering other fish species).


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## wind1

Have done a water change this morning. I only managed 30% due to time constrictions and a back issue (back and forth with a heavy bucket of water). Should I do another 20% later or does the whole 50% need to be done in one go to make it beneficial? Droopy tail has come out of hiding and he and ragged tail went wild swimming around with all the others after the water change. I haven't seem them that active for the last couple of days so not sure if that is a good sign or not?! My husband is picking up some melafix for me today so I will put that in later as well.


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## ameliajane

The 30% will be fine - please don't injure yourself!
Many fish do tend to get quite excited when they have a water change. It might be because they find it stressful but it's more likely because they enjoy it. White Clouds like fast moving water so they do seem to enjoy the process of a water change. Many fish will display and start to breed directly after a water change too.


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## wind1

Do I need to take the carbon out of the filter when I put melafix in? A couple of the White Clouds were displaying after the water change this morning. I haven't seen them do that before. The danio's were wild, they dart about so fast.


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## NaomiM

TBH I'd take the carbon out and leave it out - replace it with some more normal media, it's more beneficial. Carbon is only really useful if you need to remove meds or other chemicals from the water.


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## wind1

I've taken the carbon filter out and replaced with just normal filter sponge. The 2 poorly fish are looking more lively although droopy tail still keeps hiding away somewhere but they are both swimming around much more than they have been so that's a good sign. I have just put some melafix in. Thanks again for all the help both of you.


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## wind1

Next question! Should I carry on doing water changes daily whilst adding melafix? The fish with the droopy tail is still more active and has eaten. The one with the ragged tail has stopped swimming around again and when I fed them did not eat even though some flakes were floating past within reach. It is a lot smaller and thinner than the others. I did also see one of the Danio's headbutt it a couple of times.


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## NaomiM

Sounds like your minnow is being picked on due to being a smaller and weaker fish (fish are mean like that!) in which case unless you have a seperate tank for him, there's not a whole lot you can do about it  Keep testing the water daily - you only need to do extra water changes if your tests show any ammonia or nitrite present - and keep dosing the melafix to give him the best chance of recovery. Crushing a clove of garlic and adding it, together with its juices, can also be beneficial as it's an immunity booster and an appetite stimulator - even if he doesn't eat it, the juices in the water may do him some good. (Remove the remains of the clove after 24 hours or so to stop it polluting the water.)


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## wind1

Situation in the tank still the same. The 2 poorly fish are still behaving pretty much the same although I think droopy tail is a little more active. I have seen one of the Danio's chasing him a couple of times. I intend adding 5 more Danio's at some point and as you say a bigger shoal might be better would I be ok to add them now, do you think it would stop the bullying or should I wait until I see what happens with the 2 poorly White Clouds? They are still showing no signs of fungus, the ragged tail has not got any worse, they are just a bit droopy and quiet. Water parameters are still at 0 for ammonia and nitrite, nitrate 40 and I am adding melafix daily.


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## NaomiM

I'd give it another week or so. It's generally recommended to wait 2 weeks between each addition anyway to let the filter catch up - when you add fish there will be a certain amount of ammonia in the water due to the increased bioload, even if it's at undetectable levels and being dealt with by the filter before it becomes a problem. The filter bacteria will quickly increase to deal with it at the rate it's being produced, but the water quality will be ever so slightly lower for a few days after an addition, which isn't what your poorly minnows need at the moment. Also, just in case there is any kind of fungal or bacterial issue causing or contributing to the problems (possibly brought from the shop with the recently-added minnows), you don't want to be exposing any more fish to it - and vice versa, when you introduce new fish there's always the possibility that they'll bring some 'nasties' with them.

On that note, I'm not sure how you've been acclimatising new fish, but just in case you weren't aware, it's best not to let any of the water from the bag into your tank, just in case there's any bacteria etc in it. (I didn't know this when I first started fish keeping, and managed to accidentally introduce columnaris bacteria, which wiped out most of my stock  )


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## wind1

Ok I'll wait, there's no hurry for them. As far as adding new fish go, I have been doing it totally wrong up until now (on the fish shops advice, something else they got wrong!), ameliajane advised me on this the other day so the next lot I get I will be doing it properly.

Can I ask you about water changes, you said to change at least 20% each time, can I do this in 2 stages so 10% twice a week or would that not be the same as 20% once?


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## NaomiM

Yes you can split it into two, but if you do this, each one should be slightly more than half the weekly amount. Think of it this way - if you did 2 x 50% changes, you wouldn't have changed 100% of the water, because the first change would have removed 50% of the old water, but the second one would have removed half of the original water and half of the newer water from the previous change (if that makes sense!)

20% is a minimum anyway - I personally change around 30% each week in each of my tanks. So around 15% twice weekly would be fine, possibly increasing slightly once you are fully stocked


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## wind1

These fish are stressing me now! Since yesterday both poorly fish went missing. One I cannot find anywhere, the other one I found behind the filter, he had managed to hide himself in a groove at the back of the filter so was hard to see. He came out every now and then and sort of floated at the side of the filter. His tail has almost completely gone now. I don't know if he was the one with the ragged tail or the one with the droopy tail as I can't find the other one to compare him with, although he doesn't look as skinny as the one with the ragged tail did so I'm thinking he is possibly the droopy tail. So, he either has fin rot or one of the danio's has bitten his tail off. I have looked everywhere for the missing one, I have taken out the ornaments, opened up the filter, no sign of him. One of the ornaments is a lighthouse which is hollow so the only thing I can think is he has hidden himself inside there but I have tried washing it out (in the tank water) so I would have thought it would have flushed him out. If he's dead in there will he pollute the tank? What should I do with the one with no tail, I have taken him out at the moment because I'm worried if it's fin rot the others will all get it. I don't know what to do??


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## NaomiM

Doesn't sound good  Keep a close eye on all the tank inhabitants and on water test results. As for the one with no tail, it sounds like the kindest option may be to euthanise him  The most humane way to do this is using clove oil - a quick google should give you the method if you decide to go down this route.

Do all the other fish still look fine?


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## wind1

Yes all the other fish look ok at the moment. What about the missing one? Will it pollute the tank if it's dead somewhere? Would it bury itself in the gravel do you think? 

I will get some clove oil tomorrow


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## ameliajane

Sorry things have turned out this way. 
If all the other fish look ok I wouldn't panic. 
It may well be that these two just did not cope well with the transfer and were a bit weak and so were picked on by one or more of the other fish. You may not have seen this happening as attacks often happen at night. 
Fish are often inbred and bred in quite poor conditions and then transported long distances to the shops. The final transfer into the home tank can be the last straw for some. These two may even have had underlying health problems that meant they were just not viable, no matter how hard you tried to save them. 
If you can't find the other fish I'm afraid it's possible it has been eaten in the night - although bear in mind fish are very good at hiding - it may yet turn up again. If you're worried about pollution just do daily water tests for a few days.


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## NaomiM

Ditto to ameliajane. Sorry this has happened - you've done all you could for them.


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## wind1

The poorly fish died overnight. The missing one has not appeared. Another one in the tank has a chunk missing from the end of his tail now. Should I take him out? He is swimming around happily with the others at the moment. How do I know if it's fin rot or not? The pictures I have googled for fin rot don't look like what my fish have really as the tails with fin rot look very ragged, these 2 look like the fins have just been cut off cleanly. I am going to phone the fish shop later and tell them as these 3 are from the latest batch of 5 bought there ten days ago so I'm thinking there was something wrong with them. Water parameters still fine this morning, that's the annoying thing, my water has been fine all along but still losing fish. Feeling quite disheartened with it all now.


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## ameliajane

So sorry. Aquariums are actually very easy to manage once they are up and running and settled but getting through teething problems in the early stages can be very frustrating and you have had some bad luck.

It's hard to be sure but it's sounding increasingly like you have a fin nipper in there.
It's most likely just one individual fish and almost certainly one of the Danios, although any fish can fin nip.

Danios can be fin nippers, particularly if they are kept in small numbers in relatively small tanks with smaller tank mates that are occuping the same level in the water. This is not very helpful to you now but they are really best suited to longer tanks with plenty of open water to themselves and lots of other Danios to chase.

Have you seen _any _signs of any of the Danios chasing the White Clouds? What may look like fairly harmless brief chases during the day could turn into the odd bit of fin nipping, especially at night when the White Clouds might be less alert.

Ideally your White Clouds and Danios would be separated to see whether the problem still occurs, but I appreciate you probably only have one tank. You could try filling the tank with lots of tall aquarium plants and upright pieces of wood - it will provide the White Clouds with places to hide, ensure the fish are not constantly in each others eye line and give the Danios something else to think about as they negotiate the obstacles.

Ultimately, if you have a determined fin-nipper the only real answer is to identify and re-home it.


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## wind1

I fed them earlier and sat and watched them. The one with a bit of his tail missing did not eat at all, he just sort of floated below the water line whilst the others all darted about eating. After eating the danio's went wild swimming back and forth together, the white clouds all grouped together in the top corner of the tank and as the danio's went that way they just swam straight through them scattering them. There was a little chasing going on, then white clouds would regroup and head back to the top corner. After a while the danio's settled and the white clouds starting swimming around again. So, I'm guessing it is that the danio's are bullying the white clouds. They didn't seem to be doing this before I added the 5 new ones. They were much smaller than the others so maybe they see them as easy target. I'm cross with the shop because right at the beginning when I was starting the tank up, I asked if the two could live together and was told yes in my size tank they would be ok.

I have taken the injured one out but not sure if I should just leave him in there as he will be stressed being on his own so will likely die anyway.

I don't think I would be able to identify the fin nipper as they all look the same to me.

I'm thinking maybe I'll just add more danio's now in the hope that a larger shoal will behave better.


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## ameliajane

wind1 said:


> I'm cross with the shop because right at the beginning when I was starting the tank up, I asked if the two could live together and was told yes in my size tank they would be ok.


If there was just one piece of advice for you and anyone starting out in keeping fish it would be to _totally ignore_ _everything_ the aquarium shops tell you. Do your own research.

I got into keeping fish after buying a friend's daughter a fish tank to keep goldfish. The tank must have held about 12L and when I asked the shop how many goldfish we could put in the tank they told me seven would be ok!!! Not surprisingly all the goldfish died as did their replacements and when I finally began to research to find out why they kept dying I was horrified. I know Naomi had the same sort of experience too. I think we've all fallen into the same trap.

I hate going into aquarium shops now because every time I do I hear terrible advice being given out that will lead to certain death for the poor fish and disappointment for the owners.

It's difficult to know what to do now. Ideally either the Danios or the White Clouds would be rehoused. Adding more Danios _might_ help but it's by no means a certainty, especially if it's just one individual fish that's doing the nipping - an aggressive individual can be _very _persistent. I also wonder whether the reason the smaller, new White Clouds are being targeted is because they are still small enough to be regarded by the Danios as potential food.

If you've decided to try adding more Danios It would still be worth also adding lots of tall plants and/or tall pieces of wood to allow the White clouds opportunities to escape and to provide distraction for the Danios.

...or you could always treat it as an excuse to have a second tank...


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## wind1

I've just added 2 more tall plants at the back of the tank, this is where the chasing seems to happen so hopefully they will help. I have only recently got rid of a small glass tank which I had my first goldfish in, and 2 filters, a fluval 1 and a fluval 2. Why did I get rid of them, I don't know. How annoying!! I really don't want to be starting up a 2nd tank, I don't know where I would put it so the minnows are going to have to stay put. What do you think I should do with the one I have taken out? Should I put it back in the tank or keep it in the container and see how it goes?

Thank you so much for all your help, I am learning so much from you and Naomi, I will never trust the fish shops again, although it's difficult when you want to go and buy fish, how do you know if they are good stock or not?


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## NaomiM

Sorry you're having a tough time with them at the moment 

Always a tough call as to whether to take an injured fish out or not, especially if you don't have a spare tank to put him in. What have you got him in at the moment? Bit of a long shot, but if you could get hold of, say, a tall piece of perspex with small holes pierced in it to allow water through, you could partition off a corner of the main tank for him?

Adding more danios may or may not solve the problem, but personally I'd try ameliajane's suggestion first of adding extra plants and decor to break up lines of sight. You don't want to add more danios only to find that the bullying continues and you end up having to take all the danios back to the shop (as happened to a friend on another forum).

Edit - sorry for cross posting, I started typing this reply a couple of hours ago and got distracted before I finished!


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## wind1

The missing fish has surfaced but it was dead. It looked like it had been nibbled at and had no tail at all, poor thing 

The other poorly fish is in a plastic container at the moment filled with tank water. I don't have any perspex and have been trying to think of what else I could use. The only thing I can think of would be a plastic milk bottle on its side with small holes, somehow fixed to the inside of the tank. I could use a 4 litre one, do you think that would be suitable?

Just had another thought, how about a hatchery?


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## ameliajane

If you're going to try a hatchery I would try a net one - the plastic ones don't always allow much water circulation and pollutants can build up. And test the water in it anyway to make sure it's working ok.

The fish should be fine in a large plastic container until you can find a way to get it back in the tank but you need to do very large water changes at least once a day, syphoning up any bits of waste on the floor of the container first. Adding an airstone, if you have one, will agitate the water surface and so increase the area over which oxygen exchange can take place. And feed only the tiniest speck of food - the fish only needs a single bite to eat whilst it's in there.

If you can get a small filter to keep as a spare for such situations it is very helpful. You don't need a tank - a clean, new bucket or large container will do. Then if you need to use it you can fill the small filter with medium from your tank filter so you have an instantly cycled filter.


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## ameliajane

A DIY tank divider:
http://www.instructables.com/id/Fish-Tank-Dividers/
The canvas you'd find in craft shops for cross stitch type projects.


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## wind1

I was looking at tank dividers this morning online but I think a hatchery might be easier. How long do you think I should keep the fish seperated from the others for?

I did a big water change in the container last night and I'm going to do another one now.


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## ameliajane

If you can stretch to a small filter rather than a hatchery it would be better and useful if you have any need to isolate fish in the future.

The fish really needs to be returned as soon as possible. Once it looks alert and active with fins not clamped or drooping and is eating well and so long as there's no sign of infections in the tail, I'd get it back in the tank with the others.

It really is worth filling the tank with loads of plants and decor to help prevent these attacks. 

And you need to be aware that you may have an ongoing problem and you may be forced in the end to re-house one of the two groups.


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## wind1

He is swimming around and doesn't have clamped or droopy fins, he just has a chunk out of his tail. I could put him in and keep a close eye on them, I am home all day (actually home for the next 6 weeks so have plenty of time to supervise them!!). I have put extra plants in, I will upload a photo to see what you think


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## wind1

Here's the tank as it is now and also one of the fish's tail, not very easy to see but you can kind of see where the chunk is missing


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## ameliajane

Personally, if the fish is active and behaving normally I would return it to the tank and keep an eye on it - but hang on and see whether Naomi (or anyone else) will give a second opinion on this!

The extra plants you've put in will really help to keep the fish from constantly being in sight of each other and give the Minnows a chance of escaping the attention of the Danios. The more you can put in the better.

If you're going to have lots of free time over the next few weeks it would be well worth observing the Danios to see whether you can identify an individual who might be the aggressor. Sometimes it is just one fish that is particularly problematic. Although they all look the same to you at the moment you might find that with regular observation you can actually identify individual fish. If it is one fish causing this problem it's going to be much easier to resolve.


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## NaomiM

Great advice from ameliajane as usual - I don't really have anything to add. I'd agree it's probably best to get the injured fish back into the tank if it seems otherwise fine - hopefully the extra plants will help, and if you're able to add even more, then so much the better.



ameliajane said:


> A DIY tank divider:
> http://www.instructables.com/id/Fish-Tank-Dividers/
> The canvas you'd find in craft shops for cross stitch type projects.


That looks like a really good idea - I might have to give it a go some time!


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## wind1

I put the injured fish back in this morning and watched them. He just sat at the top of the tank, not really swimming. A couple of the danios and also one of the bigger minnows chased him a few times. The danios looked like they were nipping at his tail, so I have taken him out again.

Having sat watching the tank over the last couple of days, it looks like one of the danios likes to have the bottom of the tank to himself. I have noticed before that one spends quite a lot of his time at the bottom swimming around. If one of the others go down there he chases them. He doesn't seem to chase them anywhere else, only when he's at the bottom and this seems to be after they have been fed, so I'm assuming he's down there collecting up the food that has floated down there. He isn't chasing the minnows at all, they don't seem to go far enough down to bother him.

So apart from the injured fish and after feeding time, they all seem quite happy at the moment. I don't know what to do about the injured one now? Should I go ahead with the hatchery plan and see if he gets bigger and stronger, then try and re-introduce him into the tank?


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## NaomiM

That's one option, but bear in mind that fish tend to grow more slowly when they're in a confined space such as a hatchery (you see this with fry).

I've had another idea that may work for you. If you are able to go with ameliajane's suggestion of getting a spare filter, you could temporarily rehome all the danios in a large plastic container for a week or so (those big plastic storage tubs you get from hardware stores are cheap and ideal for this). Meanwhile, rearrange everything in the main tank, add some more plants/decor and move everything around. Then after a week or so, reintroduce the danios. Due to the change around, they should see it as a 'new' tank, while the minnows will have had time to get used to it. That way, the danios will see themselves as the newcomers and will hopefully be less bossy!

The spare filter doesn't need to be expensive - something like this would work fine without breaking the bank: http://www.allpondsolutions.co.uk/a...rnal-filters/450l-h-aquarium-internal-filter/


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## wind1

Filter is ordered, I have some plastic storage boxes already spare so can use one of them. Will try the separating danios option and see. Watch this space!!

Thanks once again for all your time, patience and help, hopefully soon I will be able to sit back, relax and enjoy my fish!!


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## ameliajane

Really hope it works.
You are being very patient and dedicated in trying to solve these issues.
You really deserve a bit of luck now!
Fingers crossed for you!


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## NaomiM

Hope it works out for you.

When you get the new filter, just stick around 1/3 of your existing filter media into it, and it should be ready to go.


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## wind1

Stupid question alert! How do I put 1/3 of existing media in? Do I cut the sponge?


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## NaomiM

Is there only one sponge in your current filter? Yes you can cut it (and may need to anyway if the new filter is a different size and shape), but most filters I've come across have several sponges, or a mixture of sponges and ceramic beads. (The sponge would still be the easiest bit to transfer across, though.)


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## wind1

It has 2 sponges and some beads in a chamber in the middle. I also put 2 more sponges in when I took the carbon out, but would they have been in long enough to be beneficial? and whatever I use I assume I then replace it with a new one


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## NaomiM

In that case, I'd put in one of the older sponges, plus maybe just a few of the beads if the new filter has a tray/chamber for them. The new sponges will have some good bacteria by now, but probably not as much as the older ones. (If you need to trim the sponge to make it fit, don't throw away any of the trimmings, just put them back into one of the two filters.)


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## wind1

A quick update, the injured fish died yesterday. I have been closely watching the others in the tank and at the moment it has all settled down. The 5 danios are behaving themselves, only occasional chasing of each other which I think is normal, and leaving the minnows alone. The 7 minnows all look happy and healthy and are enjoying the new plants to swim amongst. I will be adding a couple more plants today hopefully.

So, as things have settled and I haven't yet received the new filter, I'm going to leave the danios in the tank and continue to watch them over the next few days. If all stays settled then I will add the next 5 danios. At least I will have a filter ready to use if I do need to separate anyone in the future.


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## NaomiM

Sounds sensible. Keep an eye on ammonia and nitrite levels for a couple of days, as the dead fish could have caused a small spike if you didn't find and remove him straight away (BTW it's also good practice to do a water change any time you lose a fish, for the same reason). Sorry you lost him


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## wind1

The injured fish was still in the container on his own when he died due to the others chasing him when I tried to put him back in the tank. I will check the levels before I put any new fish in though.

I have bought more plants to put in today to provide more cover.


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## wind1

Have now added some leopard danios. I went to the shop for 6 but that left just one in the tank on its own so I had to have that one too, I couldn't leave him on his own. So far so good, everyone is behaving themselves and all are looking happy. Fingers crossed it will last! When I put the new ones in, one of the minnows appeared to be displaying to one of the new danios. He was following it around the tank and puffing out his fins (not sure if puffing out is the right way to describe it). Is it normal to do this to a different breed of fish? The danio appeared to be taking no notice.


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## NaomiM

Haha, the minnow was probably just showing the new "intruders" who's boss in his tank! I hope all settles down with the danios now and works out well.


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## ameliajane

When I saw you'd posted again my heart sank - I thought you were having more problems!
Really pleased to see everything is going well at last  
Fingers crossed this peace will continue.


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## wind1

Don't want to speak too soon but still going well and I am really enjoying my tank now. I have mentioned before I would like some corys and having looked at them in a couple of shops would like them even more now. Naomi, you suggested I should change the gravel for sand so I'm considering doing this. Would you mind just giving me an idea of how I should change it so I can decide whether it's worth the effort. I have googled it and it looks like I should use silica sand, how much would I need for my 90L tank? I imagine I should remove the fish, so I'm guessing I should put them into a large container with a filter (I can make use of my spare filter I bought!). How long would they have to stay out of the tank? Is sand easier to clean than gravel, I have visions of it all being stirred up when you hoover it? Last question, how many corys could I have in my tank? I have 12 danios and 7 minnows at the moment. Thanks


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## NaomiM

Really glad things are going well now 

The key to switching substrates is preparation. There's a good guide here: http://www.tropicalfishforums.co.uk/index.php?topic=37574.0

Silica sand is right - the cheapest option is Argos playsand, which I have in one of my tanks and looks good, but is very fine and needs loads and loads of washing before you put it in the tank! The best way to wash it is to put it in a large bucket, tilt the bucket at an angle and run water over it, stirring it up with your hand every so often, until the water runs clear. Be warned, this can take ages! I'd recommend doing it the day before you make the final switchover.

Alternatively you can buy aquarium sand (make sure it's silica sand, as you said, not coral sand, as coral sand will raise your pH). This comes in a variety of colours and grain sizes, and is often marked as pre-washed, but still needs a good wash before you switch it over!

Be warned, the water will look cloudy for a couple of days after the switchover, but your filter will soon clear it if you have a nice big piece of filter floss at the top of your filter to catch the dust. You may need to change the filter floss once the water has cleared.

It's very easy to clean - just hover the syphon a cm or two over the surface of the sand, and you'll see all the waste get sucked up while the sand stays where it is  The waste all sits on top so is easy to hoover up, unlike with gravel where it filters down between the stones and gets caught.

You need to stir the water up every so often to stop pockets of gas from developing - you can either do this manually with a stick etc, or get hold of some Malaysian trumpet snails, or MTS, which will burrow in the sand and do the job for you. If you ask around on fish forums, you'll probably find someone who's willing to send you some for the price of postage  Corys also help to stir the sand up and keep it clean.

Corys need to be in groups of 5+ as they're very sociable fish. You should be able to get away with a group of 5-6 peppered corys as they don't have a very high bioload, but you'd then be fully stocked


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## wind1

thank you, I think I will go for it. How much sand would I need and how deep should it be? Also what grain size? Should I put the fish back in straight away? Will they be ok if the water is cloudy?


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## NaomiM

About an inch to an inch and a half of sand is perfect - you don't want it too deep as it's then more prone to a buildup of gases. If you don't have live plants, there's no need for it to be too deep. There's a number of online calculators for working out how much sand you need to buy - I used this one I think: http://www.fishtanksandponds.co.uk/calculators/substrate.html

Grain size doesn't matter too much - in one of my tanks I have play sand which is very fine, while in the other I have this which is much coarser: http://www.aquaessentials.co.uk/unipac-limpopo-black-sand-125kg-p-2828.html Anything up to around 2.5mm is OK.

The fish will be fine if the water's cloudy  So long as the water in the temporary container you have them in is the same temperature as in the tank, you can put them straight back in.

Do regular water tests after switching over, as you will lose some good bacteria with the gravel and may have a mini cycle - if this happens, just do water changes like you did back when you first got the tank, and it should resolve itself within a couple of days. The suggestion (in the link I posted earlier) of tying up some of the old gravel in a leg from a pair of tights etc, and leaving this on the sand for a few days, will help to build up the bacteria colony again. When I changed my gravel to sand, I also dosed whole-tank doses of Seachem Prime for a couple of days as an insurance policy, as it detoxifies any traces of ammonia that might result.


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## wind1

Have been looking at different sand. I want a light colour so the corys are easy to see on it but some reviews I've been reading say that the light coloured sand ends up dirty looking or turning brown from detritus. I don't want to use it if it's going to be hard to maintain. Have you had experience of using a light colour?


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## NaomiM

Peppered corys would also show up well on black sand  My light coloured play sand does get brown patches (from algae I think), not on the surface but visible where the sand meets the glass sides. It's not too hard to remove by sticking a finger down the side of the tank and rubbing (and then the corys come and eat the particles), but it does grow back quite quickly and look unsightly until I clean it again. Corys do a great job of keeping the surface clean (I have much more debris in my larger tank which has no corys!) but black sand definitely hides the dirt better  Don't forget to move and hoover under ornaments when you do water changes though - I never realised how much dirt accumulates under them until I changed to light-coloured sand in my smaller tank!


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## wind1

I can't find anywhere that sells coldwater corys? I thought before going through the process of changing my tank from gravel to sand I would check where I could get the fish first. Everywhere I go they only have tropical and I'm being told that corys are only warm water, not cold! Any ideas where I could get some? Or is there another bottom tank dweller I could have?


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## Fishyfins

Corydoras are a "temperate" species, meaning they will do well in both coldwater (room temperature) and tropical aquaria as long as you avoid the extremes. There is no specific coldwater cory. If you want them, just get a "tropical" one and make sure you acclimatise them properly.


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## NaomiM

Really Fishyfins? My understanding is that within the cory family, there is a wide range of different temperature preferences. For example, planetcatfish.com lists sterbai cory as flourishing between 24 and 28 C, and they are often kept with discus as they're one of the few corys that can tolerate the high temperatures discus require. At the other end of the scale, peppered corys can be kept between 15 and 25 C, so fine for either temperate or an average tropical tank. I'd recommend peppered corys as being one of the hardiest and most commonly available of the cooler water cory species. http://www.planetcatfish.com/common/species.php?species_id=271

When buying, you might need to reassure the shopkeeper that the tank is in a heated room and won't drop too low in winter, as they may think you're looking for true coldwater fish (like goldfish) that can tolerate really cold temperatures (such as an unheated outdoor pond). I met a similar reaction yesterday when I told a shopkeeper I was looking for a bulldog pleco for my temperate tank - bulldog plecs are fine down to 20 C and my tank never drops below this, but as they're normally sold as tropical fish the shopkeeper was being cautious (even though in reality they prefer lower temperatures than the average tropical tank).


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## wind1

I think I need to get a thermometer and see how warm my tank is. One of the shops told me peppered corys could only go down to 22C, I don't think my tank will be that high in winter. I do have a heater that came with the tank but I have never used it. Would I be able to use that at a low temp with the danios and minnows in there?


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## NaomiM

If you stick the heater in and set it to, say, 20 C, it will only come on if the water temp drops below that, so will automatically stay off throughout the summer. That's what I do in my temperate tank  and telling the shop staff that you have a heater in there will reassure them that it's OK to sell you the fish  though whoever told you they can't go below 22 C doesn't know what they're talking about, as they actually prefer it cooler!

A thermometer is definitely a worthwhile investment too - I've found the simple glass ones to be the most reliable, and they only cost £2-3. It's useful to have one when doing water changes, to make sure the temp of the new water matches the tank.


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## wind1

That's a good idea with the heater as although we have the heating on in the winter my house can get quite cold. I can't decide now whether to get the corys or not, I'm going to have a further think about it. The only thing really putting me off is changing the gravel to sand. It seems a bit involved! I was looking at glowlight danios today and was quite tempted by them.


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## wind1

Have visited another 2 fish shops today but neither had glowlight danios. However they did have variatus platys. Would these be suitable for my tank? I have had a little read up on them and see they breed quite easily and that you should keep 2 females to one male. How about if I kept just 3 females? Would they be ok together, or 2 or 3 males? Obviously this would be instead of the danios as I am now near to my full stocking level.


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## NaomiM

2 or 3 variatus platys would be OK so long as you have the heater for winter. If you get mixed sex, they will breed, a lot - they can give birth (to live young) every 4-6 weeks. If you get just females, be prepared for them to be already pregnant - they store sperm so can give birth up to 6 months after having been with males, and multiple times, so you could experience up to 6 pregnancies from each female even after housing them away from males! They're fairly easy to sex - look at their anal fins (the one on their underside nearest their tail) - in females it's fan-shaped like their other fins, whereas in males it's elongated and points back towards their tail (they use this to deposit the sperm). Don't necessarily rely on the shop staff to be able to sex them accurately, though!

If you do get females (and therefore fry), you'll probably only get 1 or 2 survivors from each batch of fry unless you're able to catch them early and put them in a breeding trap. Don't put the females in a breeding trap to give birth, as this will stress the females and you may end up losing them. You can either try to catch the fry (which can be very tricky!) or just let nature take its course and let them take their chances - as you now have plenty of plants and hiding places, the likelihood is that the strongest few will make it to adulthood. But of course, you then need to consider whether you have room for them all...!

I've always had female platys as I'd read that multiple males will occasionally fight, although most people have no problems with keeping several males. I gave most of the surviving fry away, but have one female in my tropical tank who is now an adult (my first-generation platys have by now succumbed to old age).

My personal preference in your tank would be to bite the bullet, switch to sand and go with corys, as I find corys to be really interesting to watch, useful to help with keeping the substrate clean, and they're providing movement in a different area of the tank than your other species (plus I prefer the look of sand in a tank anyway). But I do get that you don't relish the prospect of all the hassle of switching substrates.


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## wind1

Ok, so I went for it! My tank now has sand at the bottom. It took 2 hours start to finish, the fish were out of the tank for an hour and are now all back in exploring their new environment. The hardest bit was catching them to put in the tub, and boy can those danios jump! 

I have put some of the gravel into a pop sock and hung it in the tank. I haven't got any filter floss to put in the top of the filter, I forgot you had said to do this. Will it be ok without or should I get some tomorrow? And would it be worth me getting some Seachem Prime?


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## NaomiM

Congrats!  Yes catching the fish is always the hardest part! My espei rasboras are the hardest to catch, as they can make their colour fade to practically nothing and are very good at hiding! The endlers and barbs are the easiest as they're so nosy, they just swim right into the net!

I'd put the sockful of gravel actually resting on the sand, so that the good bacteria can more easily colonise the sand 

Most filters have a layer of filter floss, which is useful any time to stop the filter getting clogged up with dust particles and solid waste, and particularly so immediately after a substrate change.

Seachem Prime is also always a worthwhile buy IMO, as it's not only a useful insurance policy at times when there's a risk of ammonia spikes, but it's also a very economical dechlorinator, as it's highly concentrated so even a small bottle will last for ages. A 1ml dosing syringe is useful to make sure you're adding the correct dosage (you can get a pack of 10 of these for 99p from ebay).

Whether or not you get the Prime, be sure to keep a close eye on water test results over the next few days 

And one more thing - I think we need some pics!


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## wind1

I have laid the socks down now, I put 2 in. My filter doesn't appear to have a layer of floss, the water in the tank is very clear already so do I need the floss? Would it be a good thing to use it in the filter all the time now I have sand? I will get some Seachem Prime and I already have syringes. I have already checked the water this morning and will do so over the next few days.

I will take some photo's once the new fish are in, the tank doesn't look very attractive at the moment with 2 pop socks full of gravel laying in the bottom! I actually really like the look of it now with the sand, I thought I might not like it as much as the colourful gravel but it looks really nice so I'm glad I did it.


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## NaomiM

Do you know the make and model of your filter? If the water's clear already and the flow rate of the filter doesn't seem to have slowed, it might be fine without floss, but in mine I find that the floss catches all the larger particles before they can make it into the main filter, meaning that I don't have to clean the rest of the filter media so often 

I love the look of sand in a tank. I started out with coloured gravel in my tropical tank, but would never go back now  What colour sand have you gone for?


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## wind1

The filter is a fluval U3. I think when I took the carbon filter out the floss may have been attached to that and I've thrown it away. The box says poly/carbon filter. I will order some from ebay, it looks quite cheap on there.

I went for light sand, I considered white but decided on natural looking in the end.


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## wind1

I want to add some Malaysian trumpet snails to the tank as well. Can I add them now or should I wait until I get the Corys? Would 6 be a suitable number to have?


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## NaomiM

Add MTS as soon as you like - they'll be beneficial right away  They do breed quite quickly, so bear in mind that you'll soon end up with more than the number you start with, but as they're tiny and spend most of their time burrowing in the sand, you won't see that much of them! If you're feeding the right amount, their numbers will increase slowly - a population explosion is a good indication that you're overfeeding! I think I started out with 10 a couple of years ago in my 70l, and have no idea really how many I have now, but I'm certainly not overrun with them. It's worth asking around on fish forums as you'll probably find someone who can send you some for just the cost of postage (which will only be £1 or so as they don't need any specialist packaging). I'd say 10 is a good number to start with


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## wind1

How long should I wait before adding the corys? I'm planning on getting 6, can I add them all at once?


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## NaomiM

Give it a week or so with daily water tests to let everything settle after the substrate change and to let the bacteria colonise the sand. Then take out the socksful of gravel, do water tests for a couple more days, then assuming all readings are fine, you're good to add all 6 at once


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## wind1

I have now got filter floss but not sure where in the filter I should put it? Also had 14 MTS's delivered this morning (I ordered 10 but rec'd 14), they have all buried themselves in the sand!


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## NaomiM

Depends on the make and model of filter, but it's usually in the top, just above all the other media  If you still have the instruction manual for your filter, it should say in there.


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## wind1

The instructions don't mention floss but the carbon cartridge had what looked like floss attached to it, I threw them out! So, I'm thinking I should put the floss where the carbon filter was. When I took it out I put extra sponges in, there will not be room for them and the floss so should I just put floss in one side and take one sponge out, or take both sponges out and replace with floss?


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## NaomiM

Just one lot of floss should be fine - you only need a thin layer, and you don't want to take more than one sponge out as you'll be losing the good bacteria in it. Give it a squeeze over the other filter media (including the floss) when you take it out, so as not to lose too much of the bacteria. If you can manage to squeeze a single layer of floss in without taking any sponges out, then better still - it doesn't matter if they're a bit squished


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## wind1

I should be able to squeeze a layer in with the sponges so I'll do that. I have been googling filters and floss and reading some very contradicting information. Some people say it's good to use, others think not very beneficial. Some say it needs cleaning/replacing every water change, others say not so often. Some say it clogs up the filter? How often do you clean yours? Do you just squeeze it out or rinse it in tank water? I also read that it should be rinsed under the tap as it does not hold any beneficial bacteria so can be cleaned that way.


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## NaomiM

Don't rinse it under the tap or you'll be putting chlorine into your filter (from the tap water) when you put it back in! I clean the one in my internal filter every water change, squeezing and swishing it in the bucket of old tank water, and replace it when it looks like it's falling to pieces (every month or so) - it's cheap enough to replace  The one in my external filter gets cleaned/replaced much less frequently, except when I'd just changed the substrate and it was full of dust/particles from the sand, when I did it more often. I can't think how it would clog up the filter unless you let it get to the stage where it's literally disintegrating. It doesn't have many benefits in terms of harbouring good bacteria, but its primary function is to reduce the amount of larger dirt particles that reach the rest of the filter, meaning that it gets less clogged up and you don't need to clea/replace the other sponges so often.


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## wind1

Ok, thank you. I have put a layer in between the sponges. I have got the new syphon now as well and it is much easier than the one I had.


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## wind1

I got impatient, couldn't wait any longer, after checking water parameters daily, all fine, here are my new corys. What great little characters they are!


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## NaomiM

Nice corys  Yes they're very interesting to watch aren't they? For lots of fishkeepers, corys end up being their favourites - someone on another fish forum I use has literally hundreds of corys, and is always looking out for different/rare cory species! Yours look like and healthy - good long barbels (the 'whiskers' at the front of their faces) which is always a good sign


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## wind1

Spoke too soon again!! I tested the water this morning and ammonia, nitrite and nitrate were a little high. Did a big water change, took the floss out of the filter and it was really dirty so washed it in the tank water I had taken out. When I switched the filter back on, it wouldn't work. I have fiddled about with it but cannot get it to run. I have put my spare filter in with as much of the sponge from the other filter I can fit in but that is less than half as the spare filter is much smaller. Now I cannot find my receipt, I've only had the filter 3 or 4 months, I never throw receipts out so it is here somewhere, I just have to find it! So, in the meantime is there anything else I can do until I get the filter sorted or replaced?

Edited: Had another go with the filter and gave the impeller a good clean, now it's working again. When I have checked the impeller before it is never dirty but looking closely at it today there was quite a lot of gunk around the shaft and also in the hole where it sits. Would it be anything to do with changing the substrate to sand and/or putting in filter floss and/or adding corys? I'm probably clutching at straws but it seems the impeller and the high water parameters have both only occurred since changing these things.


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## NaomiM

Glad you got it working again. It's scary when that happens isn't it - it's happened to me a couple of times! You did all the right things. The gunk in the impeller was probably caused by all the dust from the new substrate, and the fact that you didn't have filter floss in initially would have meant that more dust got through into the impeller. It also may have slowed the rate that the filter turned over the water, which could have led to a gradual build-up of toxins. The addition of new livestock would also have increased the amount of toxins produced (although corys have a pretty low bioload), which, combined with a slower rate of filtration, could have led to the filter not coping with the bioload. Often it's not until the filter is turned off and turned on again that the problems become evident (i.e. it won't start back up), but it sounds likely that it had been struggling for a little while.

Obviously you'll need to keep a close eye on water parameters until they return to normal, and do extra water changes as appropriate. A daily whole-tank double dose of Seachem Prime, if you have some, will also help to make sure the fish don't suffer from the elevated toxin levels, especially the corys, which are quite sensitive to water quality due to living at the bottom where the water quality is poorest. It's generally a good idea to check and clean your impeller every now and then anyway (cotton buds work quite well for this!) but it might be a good idea to do it weekly for a little while, whilst everything settles.


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## wind1

I did another big water change last night as levels were still up. This morning ammonia and nitrite are back to 0 but nitrate is up at 80. One of the corys has been very quiet, he's always been less active than the others since I got them but is now not swimming around much at all. I haven't got Seachem Prime at the moment but I have ordered it so it should be here tomorrow. I will do another water change now. Any ideas why nitrate is staying high?


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## NaomiM

Don't worry too much about nitrate - the fish you have won't be too bothered about a level of 80 for a while, and it should gradually sort itself out as things return to normal in your tank and you keep up with water changes. The elevated levels are probably just from the filter 'catching up' and processing the excess levels of ammonia and nitrite. Some of the filter bacteria would likely have died during the problems you had with the filter, and the die-off of filter bacteria also produces nitrate. So long as ammonia and nitrite are at 0, I wouldn't worry too much (though do keep testing daily, and the Seachem Prime will help when you get it as it also detoxifies nitrate) - maybe just add in a few extra water changes to help reduce the levels a bit


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## wind1

The Cory that was not very active has died  The ammonia and nitrite have been ok yesterday and today but nitrate still high. I now have Seachem prime so have added some of that today. Should I do a double dose or just single, and should I do it every day, or how often whilst the nitrate is high? I did a water change yesterday and will do another in the morning.


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## NaomiM

Sorry about your cory 

If ammonia and nitrite are OK, just single dose the Prime daily for a few days. The nitrate alone really shouldn't be a problem for them, and the extra water changes should help to gradually bring it down, but the Prime is just extra insurance really.


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## wind1

Did another water change yesterday 30% but readings this morning are still at ammonia 0 - 0.25, nitrite the same as ammonia and nitrate is up at about 80. Why are they not coming down? Would it be beneficial at all to put my spare filter in with the other one? I'm wondering if the filter is running properly, I have taken out the impeller again and cleaned inside with a cotton bud, there was more gunk in there. The sponges in the filter don't look dirty, but when I turn the filter back on after a water change I do notice it spurts out a lot of dirt which floats around the tank for a while. As I said before, all these issues have only arisen since changing the substrate, adding filter floss and adding corys, oh, and the snails. My water levels before were always perfect. It's so frustrating and I'm worried the corys will suffer.

Edited: Decided to check nitrate in tap water. It would appear I have not been reading it right because tap water came out at 80 too, however when I held it up against the card with the colours on, in the right light it was 20. So I tested the tank water again and that came out at 20 too!! Panic over, I will still be keeping a close check on it though. I've become a little obsessed with it all!


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## NaomiM

That's good 

I'd keep dosing Prime daily while you have trace levels of ammonia and nitrite, just to be on the safe side, but it looks like your tank is more or less back to normal after a 'mini cycle' caused by the filter issues.

Don't worry too much about the filter spurting out dirt - mine does this too and I've been assured it's normal. You could always tie a pop sock etc over the filter outlet before turning it back on, to trap the dirt so it doesn't blow all around the tank


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