many of the soft corals like mushrooms, zoanthid, kenya tree, colt corals don't reqiure a lot of light, some of them do benefit mind you but it's not a requirement since they are more apt to get food out of the water column than our stony brethren.
i have a 2, 15 watt bulbs - 1 actinic and 10k fluorescents - i wanted to get a compact fluorescent but some1 told me that it might heat up my water too much.