# Fish tank buffs- LED question



## Stephny691 (Nov 13, 2007)

Through my work we have a new range of LED lights from single LEDs to flood lights. We're basically trying to work out what they need to have to be suitable for aquarium use. So if any of you have the time (or the inclination) what do aquarium lights have to have to -be- aquarium lights?

I've been reading all about PAR/PUR/Lumens and honestly it makes no sense. 

Is there a market for LEDs to light fish tanks? Or are they more of a novelty? Have any of you had experience of using LEDs? Are they too expensive to be considered? We're currently putting them through testing to see if they will support plants, but we won't know about that for a couple of weeks yet. Any thoughts?

Thanks in advance


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## hawksport (Dec 27, 2009)

To support plant life the need to be the right colour temperature


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## Fishyfins (Feb 28, 2009)

i dont know the secifics, but the output needs to be in the correct colour spectrum, temperaue, and wavelength, otherwise it will lead to massive algae growth. this is why we dont use regular bulbs in aquariums. there is certainly a market there for LEDs in the aquarium industry, they just need to produce the correct light.


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## Stephny691 (Nov 13, 2007)

Thanks Fishyfin and Hawkspot. The actual range of colour spectrum the bulbs produce is something we're looking at now. So hopefully it's an avenue we can explore!
Thanks again


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## Guest (Aug 3, 2010)

There is a rapidly expanding market in aquarium LED lighting, manufacturers such as Arcadia and Giesemann are already utilizing this technology into their products. Reef One - the manufacturers of the Bi-Orb aquariums - have been using LED technology for a few years now.

LED lighting has a larger following in the US. One of the main drawbacks is the initial expense of buying the unit. Several powerful LEDs have to be used to match the light output from a metal halide bulb.

One of the advantages however is the low amount of thermal energy produced by the LEDs, as well as the low power consumption and minimal running costs. LEDs can run for years without having to be replaced, in comparison to Metal Halide bulbs and Fluorescent tubes which have to be replaced every 6-12 months.

From an aesthetic point of view, LEDs also cast a natural looking shimmer which is otherwise only normally produced by metal halides.

In terms of business options, I would recommend focusing attention towards the nano market for now. The lower heat-output from LEDs is a bonus for fans of SPS corals, where the usual MH lighting would cook a small tank.

Programmable control units are being incorporated into LED lighting to simulate different lighting situations experienced under different weather conditions.

Just to explain what all the technological words mean:

*Lumens:* This is the SI (International system of units) unit of luminous flux. In layman's terms, this is the actual amount of 'visible' light produced by the light source. The higher the number of Lumens, the more powerful the light looks to the human eye.

The number of Lumens per Watt can be calculated by dividing the number of Lumens by the wattage of the light itself. In many cases, LPW can be more important than the usual Watts per gallon (WPG) used in fishkeeping.

*PAR:* This stands for Photosynthetically Active Radiation. This is the spectral range of solar light energy between 400 and 700nm (Nanometres) required by aquatic plants (in both marine and freshwater environments) for photosynthesis. The wavelength of the visible spectrum (that is, light that is visible to the human eye) is measured in Nanometers (nm). Green light (the part of the spectrum that is most visible to the human eye) has a wavelength of 495-570nm. Ultraviolet light (including UVB and UVA) is invisible to the human eye and has a wavelength of less than 450nm. You may notice that UVB/UVA tubes have a purple/violet tinge to them when lit.

*PUR:* Or Photosynthetically Usable Radiation. This falls into the wavelengths of 400-550nm and 620-700nm. PUR is the segment of PAR that is absorbed by Zooxanthellae (a type of flagellate protozoa that thrives in the tissues of many invertebrates, such as photosynthetic coral species) photopigments (i.e chlorophyll) to stimulate photosynthesis.

When put into practice, PAR is measured in micro-moles or micro-Einstein. The sun for example emits a PAR reading of 2000mE. PAR readings fall as the reading is taken further away from the light source. In an aquarium, the way the light source is mounted dramatically affects PAR readings. The PAR range of 400-700nm includes green, blue and red parts of the visible light spectrum.

For most aquatic plants, the minimum PAR level for most plants is around 30 micromoles. The PAR readings will increase as more light is put over the tank.

Kelvin is the colour temperature of the light source, and is measured in Kelvin degrees. The lower the Kelvin rating, the redder and warmer the light source appears. Typical daylight has a colour temperature of around 6500K, whereas a candle flame has a colour temperature of 1900K.

For aquatic plants, LEDs should have a Kelvin rating of around 6500K to replicate natural daylight. For corals, LEDs with a colour temperature of above 10000K are better. 'Actinic' LEDs typically have a Kelvin rating of around 20000K and above, and are used to simulate a moonlight effect.


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## Stephny691 (Nov 13, 2007)

Ok now that is useful.
I have 2 products that may be able to be converted in some way.
One is individual spotlights or grouped spotlights (multiple LEDs in one spotlight) with a Kelvin of 3200K/7000.

Or a strip light with a Kelvin of 3000/5000K.

Now does this mean that you could multiple of these spotlights or striplights to give you the correct Kelvin? 
I'm thinking of trying to send a few out to our local universities and getting them to try them in their labs to see if they replicate natural light well enough for this sort of thing.

Unfortunatly the guy here trying to sell them knows nothing about them and I'm starting from scratch and learning it all on the fly! So I'm probably talking nonsense. 
Brilliant help though thank you.


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## Guest (Aug 3, 2010)

By combining several LEDs with different Kelvin ratings, you will eventually be able to produce a light source with the correct Kelvin rating, depending on how many of each particular LED are used. I'm not aware of any way to physically measure the Kelvin scale, unless someone would care to enlighten me.

However, a mixture of 6500K and 20000K LEDs would cast a yellow-hue over a marine aquarium (for example), which isn't very desirable in this case. Such a combination would be better over a freshwater system. Then again, consumers need to have the ability to switch off different LEDs, which calls for either two power supplies or two independently wired circuits with each one having their own switch. I'd prefer the former, as this means that LED circuits with their own power supplies can be switched on and off automatically by a wall timer, unless the entire circuit was controlled by a computer with an integrated timer; in which case only one power supply would be needed.

One of the main problems is that people are already using the likes of LED rope and LED strips over aquariums. If you could concoct something using good quality LEDs in a rugged, water-resistant housing at competitive prices, then it could gather a considerable amount of interest.

Does your employer manufacture LEDs? If not, the Cree XR-E's are well thought of in aquatics.


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## thesunroom (Sep 2, 2010)

I recently bought a 2 metre (underwater!) led strip that is controlled by infa red remote and changes colour! It cost around £70 but worth every penny imho. I will check where I got it from if anybody is interested. :thumbup:


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