Doug McIntyre just gave a presentation on lighting. Doug's preference for lighting would be an electronic ballast from IceCap for the double ended
metal halide bulb 250W 10,000 Kelvin and the use of actinic fluorescent bulbs.
Ironically, the bulb which benefits SPS and LPS corals the most is the 10K HQI bulb, which has a whitish yellow-blue color. The second best bulb is the Iwasaki 6.5K bulb, which gives off a yellowish-green color.
If you check our ARC website you will find the rest of the story.