check out my algae scrubber thread some guy recommended me the red blue bulb its 10 watts from ebay i just ordered 2 and got them today there like 16 bucks each and the reviews are great on them
My Kessil h150 purple spectrum was the most productive lamp I've ever seen over a refugium. They're also pretty cheap, especially used off eBay. I think I paid like $48 for mine in great used conditii
Led is adding the least amount of heat as far as the amount of lumens you get goes. Any time you add anything that runs on electric it's going to add some heat.
LED for home use, though say they are 6500K and may look light the right color to the eye, may be completely missing the right wavelength for plant growth as the peaks may not even be in the right spots for photosynthesis. Regular florescent lights that rated for a certain K have a broad wave on the color chart that overlaps and covers the right spot. LEDs don't have that wave and is very specific on where the light peaks, and that doesn't have to be where the chloroplast wants it, ie 880 for red or 450 to 480 for blues. (not exact numbers). Unless someone says a certain brand of LED for a certain color works on plants and has tried it, you'll just be wasting electricity.
this is what I use on my algae scrubber, Have a couple, one lasted only a year since salt got it the wiring, the other is doing better. Massive growth. Plant only, no corals, unless you want to get the blue one, thought it states 450, the peak may be too narrow for corals.
The one listed by "the meat" looks good, since its water proof.