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Reef Mag » Why DIY An Aquarium LED Light?

Why DIY An Aquarium LED Light?

Why go to a lot of trouble to DIY my own lighting fixture? Simple. LED lighting has so many advantages for use as aquarium lighting.

LED Lights Produce Cool Light.

For most of us the summer months bring issues with keeping our temperatures down in our aquaria. Metal Halides and T5 fixtures put a lot of heat into our systems. They emit light at wavelengths that heat our water up. LED lighting does not emit enough of these wavelengths to make any perceptible rise in water temperature occur. This has a huge knock on effect in saving energy from running fans / refrigeration units and replacing water lost through subsequent evaporation with RO water.

This is not to say that LEDs do not produce heat. They do. In fact it is one of the biggest hurdles to DIYing LED units. You must remove the heat from the LED via large heat sinks. The bonus is you get to vent this heat away from the aquarium.

There is a school of thought that states the flip side of the cool light is that in Winter months you need to supplement heat into the tank via heaters which consume energy in their own right. This is true but most people heat the environment an aquarium resides in and equipment like return pumps and powerheads already emit quite a lot of heat into our systems. Overall it is a lot easier, more efficient, and quieter to stabilise a temperature that is slightly below the optimum level than it is to cool it from above that level.

LED Lights Have A Much Longer Lifespan

The Cree MC-E LEDs I intend to use maintain an average of 70% lumen maintenance after 50,000 hours of use. That means running them for 12 hours a day for almost 11½ years before they drop below 70% efficiency. Let’s be honest, in reality they will almost certainly outlast the average reef setup. How many halide or T5 bulbs would you change in that timespan. I’m guessing quite a few pennies worth. Always factor that in to the cost of a LED build. Forget how much more energy efficient LEDs can be, just not having to change bulbs every 6 months is the biggest saving you will make.

Durability, Dimmability

You can drop a LED. Knock a LED. Probably even stamp on a LED and it will still work. I don’t recommend the latter but you get my drift.

LEDs are instant on and instant off. No effect on lamp life. LEDs are easily dimmed by a number of approaches. In fact, one way of dimming LEDs is to turn them on and off faster than the eye can detect.

Safe, for You and the Environment

Most of the LEDs on the market today operate from a DC current at low voltage. This greatly reduces the risk of electrocution. Mains voltage LEDs are on the market but I do not recommend these for DIY use. In such a specific application there is no advantage in the mains voltage LED units.

LEDs also contain no mercury and have limited transport costs.

Configurability: compact, directional lighting

LEDs are tiny. They have a multitude of easily accessible lenses and reflectors to suit your needs. I am making full use of this property in my fixture. Typical MH or T5 lighting will almost always suffer from light spillage and therefore also wastage. I also find light spill quite aesthetically displeasing.

More PAR per Watt?

At this point in time LEDs are only just overtaking MH and T5 fixtures in terms of Lumens per Watt. So anyone saying LEDs are more efficient and then quoting Lumens is, in my opinion, off the mark.

As reef keepers we are actually more interested in Photosynthetically Available Radiation (PAR) that Lumens. In fact PUR is an even better measure but it is hard to source metering equipment.

in my opinion, LEDs should produce more PAR per Watt than equivalent MH and T5 fixtures. It’s a bold statement and there isn’t easily available data to compare side by side and like for like. What we do have are spectral graphs and PAR readings from LEDs running at a known Wattage. It is logical to extrapolate from this that you do get more PAR as a percentage of total light emitted.

Commercial Units?

So why not buy an existing commercially available unit? Most just do not fit my requirements. Many available in the UK do not run LEDs at their maximum output. The beam angles are generally far too wide for my purpose. Many are quite simply over-priced. I understand the need to recoup development costs but LEDs are actually inherently cheap to produce. Many do not have a dimmable interface and timer built in. LEDs are easy to source for the DIYer. After that if you can wield a soldering iron and do some rudimentary maths then you are ready to go.


So these were my reasons why I wanted to build a LED fixture. In my mind they are overwhelming. So onto the hardware…

5 Responses to "Why DIY An Aquarium LED Light?"

  1. Craig says:


    I’ve been reading your DIY LED marine lighting thread with interest. I’m intending to use LED’s myself over a new 100 gal system but I’m having trouble sourcing the bits in the UK. I find plenty of hits for Cree sellers in the USA but nothing in UK. Any chance of you adding a few links to the company you bought the Crees and reflecters from please?

    1. admin says:

      Sure thing Craig. I really need to finish this article series and I will post the links to the EU based retailers. I’ll try and get it done tonight.

  2. the great thing about LED light is that they do not generate lots of heat;*,

  3. steve says:

    hi, i have just read some messages from craig about cree led from the UK. any chance you could forward the web sites to me so i can purchase some. thanks for your time, great site. steve

  4. admin says:

    Update on where to buy. I will link the power supply in an update shortly.

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