One possibility is to use a 10 inch square aluminum plate as a heat sink, and attach 9-10 strips of SMD5630 LEDs side by side to the face. With that right on top of the tank you should get good low-medium to medium light intensity. I would use one or two strips of green and red SMD5050 LEDs mixed in, to get better color rendition, with the others all cool white. See http://www.plantedtank.net/forums/showthread.php?t=545113&highlight=smd+5630 for my results doing that. It is a pretty easy project.