Spectrum Spectrum is an important consideration when choosing a light. Light in the range below 380 nm has been shown to inhibit calcification, while light in the 550nm range seems to most correlate with calcification. Light in the blue range also stimulates photo-respiration and amino acid synthesis. The general consensus is intensity not spectrum is more important. Making a Decision Before you choose a lighting system, you should first decide on the type of corals you want to keep.
Different corals come from different depths and require different intensities.
In fact as the popularity of SPS grows, I see more and more going to 400w. But there are other options. But bulbs are inexpensive and readily available plus little heat is transferred to the aquarium. The 96w Power Compact Flourescents have come onto the market and show a great deal of promise. 96w PC's come in 2 and 4 bulb retro-fit kits.