Like stated, 6 bulb T5HO, MH, or LED. I would recommend the taotronic LEDs as they have been very successful keeping anemone and sps coral by other members of the forum, though there are many other LED options out there.
I wouldn't try it with a 100 gallon tank. Smaller, shallower tanks would be able to get away with a 4 bulb unit. I stick with my 6 bulbs and up. I'd just wait until upgrading light fixtures and let the tank gain more maturity.