Last week I put together a new LED lighting upgrade for my 8-gal Hex freshwater aquarium. The 8-watt screw in fluorescent wasn’t putting out enough light to grow plants. It might seem like 1-watt/gal would be enough, but the bulb is omnidirectional and the reflector was garbage, I probably only got 4-watts to the water.

The new setup uses 2 white and 2 royal Luxeon Rebel High Power LEDs. I obtained them from Sparkfun Electronics on a nice breakout board. The board makes them easy to solder and mount and I recommend it for prototyping and maybe final product. Sparkfun now sells the whites as a 3-in-1 board. Note that you can get most items cheaper from Digi-Key.

I drove my 4 LEDs with a 15V, 1000mA power supply I had lying around from some other electronics device. I wired the LEDs up using a “BuckToot” LED constant current driver. This regulates the current to the LEDs and provides a more steady light. They are run at 350 mA when on max. I also included a potentiometer inline with the LEDs to allow me to turn down their brightness. This is a nice feature as these LEDs are BRIGHT. In larger setups I also suggest wiring blue and white LEDs separately with independent potentiometers to allow the blue/white levels to be fine tuned.

I used a barrel jack to allow the AC adapter to plug right in. The BuckToot is visible center with the pot below it.

I mounted the 4 LEDs to an aluminum plate I had lying around and then I added a finned heat sink for good measure. This keeps the setup from getting too hot, but I may add a fan to bring temperatures even lower.

Installed in hood of 8-gallon hex.

For more info, check the Lighting forum.
Sparkfun Electroncis
Digi-key Electronics