I'm a tinkerer, and have built several LED projects. My latest is a scrubber light for my horizontal flow scrubber that allows me to dial in each wavelength known to promote chlorophyll production across the range of marine algae. I did a lot of reading and research, and ran across a commercial system built by Phillips Lighting that uses 3 tunable bands of LED light to grow algae for food and biofuel production. My reading led me to decide on 445 & 460nm (blues), 630 & 660nm (reds) and 6500k white LEDs. eBay vendors supplied the 3w LEDs, power resistors, and PWM dimmers. Got 10 each of the LEDs, the resistors, and 5 dimmers. Ordered 120 degree lenses for the LEDs. Total outlay, less than $40. I use 1"x2" 1/8" wall rectangular aluminum tubing for all my heatsinks. 20' of the aluminum was $60. I have built several fixtures out of the tubing. Works great even running 20 10w LEDs on a 4' light. Power is a surplus PC power supply using the 12v output. Timing is by an Oktimer THC15a programmable industrial controller. Pics below:
Command and control
Light laying across control board for photos
445nm
460nm
6500k
630nm
660nm
All on
Inside the scrubber