I have 2 1 watt 10K LED's that light mine. They grow plants like crazy and give way more than enough light for my guys. Tank is 36" X 12" X 18"(height). Hooled them to an old PC power supply given that they are 12 volt. Entire light setup cost me about $20 which included the power supply, LED's, heatsinks and fans. Used the old style processor heatsink and fan setup and high temp siliconed the LED's to them. They do not however emit a lot of heat (except for about 2 inches in front) but then my place is always really warm so I don't need an external source.