Hi all. Just my 2 cents. Im an EE. I did some research online and built a set of LED fixtures using the no name "3W" LEDs off ebay. Based on the light spectrum over a tropical reef at the equator, I picked 465nm, 450nm, 410nm, and 10k wavelengths. Ive got 5 of each staggered on an rough extruded aluminum scaffold that I got from Home depot, one 18inch length for each side of a 55gallon. I control them with an arduino mega 2560 sending four individual pwm signals to CAT4100 series LED drivers from ON semiconductor. I limit the max current to 700mA, and the PWM to between 3% and 90%. I wrote code for the arduino that simulates the diurnal cycle of the sun and translated it to PWM duty cycle so the the LEDs automatically cycle throughout the day with max intensity at noon. I added a moonlight cycle as well using a real time clock. Sorry for the run on description, but to make a long story short, Ive had it running for about 8 months and have had great results. Corals adapt to their environment, if you choose the key wavelengths, 410, 450, 460nm, they can adapt and be happy. My corals are all frags and have at least doubled in size since I started using the LEDs.