# Black algae



## Deva87uk (Feb 9, 2014)

Hi everyone,

I'm new to the whole fish keeping scene so I was wondering if someone could help me. 

My tank has been established now for well over a year, I have 12 fan tails, 3 Mickey Mouse guppies and a danio in a 3ft tank - I know I need more!!

I've been fighting a black algae problem for a while now, even resorted to changing everything in the tank bar the fish and did a 50% water change as well just to try and get rid of it but it's come back?!?

Does anybody know what I can do to get rid of it? Maybe an algae eating fish? I don't know! 

Thanks, Melissa


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## NaomiM (Sep 22, 2012)

Hi Melissa,

Just to clarify - when you say fan tails, are you talking about goldfish? Because if so, a 3' tank is only really suitable for 1 or at most 2, due to the size they grow to and the amount of waste they produce (which could be feeding your algae problem). Also they're coldwater fish, so if you're keeping them at the tropical temperatures the guppies require, their metabolisms will be in overdrive, compounding the problems.


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## Deva87uk (Feb 9, 2014)

No they are tropical fish. I've added on a photo so you can see


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## Phoenix24 (Apr 6, 2013)

Ditto Naomi - unless that 3 ft tank is about 10ft high!

Algal problems are usually a result of too much nitrates and too much light. Do you have lighting on the aquarium? If so, turn it off - you only really need it for viewing unless you are actively growing a live plant aquaria (in which case there are special bulbs and plant additives that don't encourage algae). If you don't have lighting, it could be that there is too much natural light in the room (direct sunlight from a window, perhaps).

Because you say it is black algae, I wonder if in fact it is a fungal or bacterial in origin. You will need to scrub either of those off with a clean scraper (and rinse in pre-treated tap water ie with a water conditioner such as Prime... are you using one of those?).

You need to test your ammonia, nitrite and nitrate levels, too. Do you have a water testing kit? 

In the longer term, if you have 12 fan tailed goldfish in there you need to re-home at least 10 of them, regardless of the cause of the black algae.


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## Phoenix24 (Apr 6, 2013)

Having just seen your reply - what species are the fantails exactly?


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## Deva87uk (Feb 9, 2014)

I think they may be guppies


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## Deva87uk (Feb 9, 2014)

Yeah I do a 25% water change and use tap conditioner weekly as well. Test strips always come back as clean as a whistle and I get pets at home to check it weekly as well.

This is what it looks like


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## Phoenix24 (Apr 6, 2013)

Ah yes - guppies, no problem there then! I would probably not get any more danios though, as these typically prefer slightly cooler water to the guppies. Depending on the pH of your water, you could look at some other species that might be compatible with the guppies.

I have seen that kind of black algae before - but only in the tank I had that had a lot of light. Its not quite clear in the photo, but it looks like open glass at the back? You could try getting a dark coloured aquarium background, and wrap it around at least on of the sides that gets the most natural light. And like I said, if you use lighting then turn it off - the fish really don't need it (in fact many species prefer unlit tanks, and colour up better in lower lighting levels).

Take the ornaments out and give them a scrub (with a clean (ie never touched a chemical in its life) scrubber, in pre-treated water). Perhaps instead of more danios you could investigate fish that are plant eaters. As you have a fairly large tank, you might be able to think about some of the loaches and smaller plec species, but there are other fish that happily nibble away on anything plant (in fact there's one just come into our LFS that NEEDS plenty of algal growth to survive - I will see if I can find what that was). Just be aware that once you get a plant-eating fish you can say goodbye to any other plants in the tank. 

Try cutting down the lighting first, and see if that helps.


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## Deva87uk (Feb 9, 2014)

I don't actually like danios - the one I have was a gift for my 3 year old lol 

I'm wanting to get some clown fish and maybe some more guppies but I want to get this algae under control first


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## Fishyfins (Feb 28, 2009)

Deva87uk said:


> I'm wanting to get some clown fish and maybe some more guppies but I want to get this algae under control first


Clown fish are marine fish, and would not survive for more than a few seconds in a freshwater tank, so sadly not really an option.
Unless you mean clown loach, in which case they need to be in big groups, and even a single one would grow far too big for the tank you have, so again, sadly, not really an option for you 

Algae of any kind (including the filamentous hair algae you have) require 2 things to grow - food and light. An excess of either can lead to algae blooms.

For the light, the best bet is just to reduce the amount of light the tank gets. To be honest, the fish dont need the light, its only there for you to see the fish. i usually dont light my tanks for more than 6 hours a day, on an evening, when im looking at them. it not only helps reduce algae, but saves electricity as well! I usually advise lighting the tank for no longer than 6 hours a day. This is less than the daily photoperiod needed by most algae, thus limiting its growth. If your having a particularly bad issue with algae, maybe try putting the entire tank into darkness for a while (a week or two, maybe by putting a duvet over it or something). This will kill off most algae in there, and allow you to start afresh with it. (though if you have aquarium plants, you will lose them)

Also with the lighting, when was the last time you changed the bulbs? Incandescent strip lightbulbs have an active lifespan. Over this life, the spectrum and wavelength of light produced changed subtly (inperceptable to humans) from a wavelength/spectrum that supports higher aquatic plants, to one favoured by algaes and lower plant forms. Put simply, over the course of its life, the bulbs output changes from light plants can use, to light algae can use, meaning more algae later on. This change generally happens around the 6 month period, and so aquarium bulbs should be replaced about ever 6 months, whether they are producing light or not. A new bulb should shift the spectrum back to the plants instead of the algae.

The nutrient problem can be a little harder to fix. First, it depends on how much you feed. Uneaten food can break down, leading to algae, and fish waste itself helps feed it. generally speaking, in an ideal world, you should feed your fish twice a day, with enough food to have them activly eating it for 3 minutes. anything left after that should be netted out the tank and disposed of. But reducing it is fine until the problem has sorted itself out.

The other way nutrients can be a problem is through overstocking. Now, you say the tank is 3ft, but not the volume. Most commonly available 3ft tanks are round about 90L in volume, and based on that, i have calculated that your tank is probably just on the edge of the maximum recommended stocking guidelines for that size tank (if not slightly overstocked). If you post the exact dimensions of the tank and the type of filter you have, i can work it out properly for you.

But obviously, the more fish in there, the more waste produced, and this waste feeds the algae. By reducing the bioload on your tank, you will reduce the algae's access to nutriment. Most fishkeepers try and keep stocking quite low to limit this algae growth. With you being on or around the maximum stocking capacity, it may be aiding the algae growth.

Hope this helps
Fishy


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## Deva87uk (Feb 9, 2014)

Hi thanks for your amazing post!

I've only just changed the strip light maybe a month or so ago. I remember this because it was an absolute pain in the backside to do! Lol. I'm quite liking your idea of putting a blanket over the tank, it may stop the cat going for it while she settled in. I'm also going to get some of the dark background for the tank although where it is at the moment the only light it gets is from the back door and the strip light. Admittedly I do keep the strip light on about 12 hours a day. Naughty me!

I tend to only feed my fish once a day as I was told to keep the waste level down that I should only feed them 2/3 times a week?! There is never anything left so maybe I should be feeding them twice a day.

The tank is 60L I think and it has a stingray filter and obviously the heater is set to 25oC. Somehow my live plants never survive very long. Is there any particular way I should be cleaning the filter because I always end up taking it out and cleaning it that way. Bearing in mind I am physically impaired.


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## NaomiM (Sep 22, 2012)

60l seems quite low for a 3', unless it's one of those wall mounted ones or something. What are the actual dimensions? As fishyfins said, if it's really 60l then it sounds like you may be overstocked.

Guppies are greedy little piggies and can literally eat until they burst, so don't increase the feeds - a pinch once a day is plenty, and it's best to give at least one starve day a week.

Regarding the filter, all I do with mine is take the media out and give it (the media) a gentle swish in old tank water - NEVER use tap water! And don't clean all the media at once - rotate which one you clean at each water change.

I'd definitely cut the lighting down, too. 8 hours a day should be plenty.

Re keeping plants alive, do they have a source of co2? The easiest way for non-demanding plants is a daily dose of liquid carbon. This is great for plants but kills algae! And remove any dead or dying plant matter asap, as it will be increasing your nitrates.


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## Deva87uk (Feb 9, 2014)

Jeez I was well out! Just measured it and it's 60cm (l) by 30cm for depth and width. Most definitely overstocked!


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## paulbeeston (Jun 28, 2009)

If you cover the tank in black bin bags front back and sides and have a total blackout for 3 days, don't even feed the fish, then that should help with the black algae.


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## Apollo2012 (Jun 10, 2013)

I have a 60l tank and bought two baby bristle nose plecs to deal with the algae, as cutting down feeding and minimizing light time to no more than 2 hours a day wasn't working, now after about 3 weeks there's barely any algae left and my baby bristle noses have doubled in size, I am getting a 200l tank in a couple months though else I wouldn't have gotten the Plecs, I have a couple peppered corys and a couple yoyo loaches too but they didn't make a difference


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