You could build your own hood and fill it with daylight flurorescents.Those bulbs are rated at 6500K--which means they are adequate for most corals. Take a look at the GARF website and check out their lighting specs. They grow spectacular coral without expensive metal halides. I think the reason is: coral animals can photo-adapt, as long as you do it slowly, which means they'll thrive once they are acclimated to your lighting system (which should at least be the right color temp).