I just bought new bulbs and man am I happy. the corals a flourescing nicely(maybe a little to much) and the tank is a nice white/blue. 4 24" ATI superblue T5 and a new Iwak(some other letters) 175 watt 15k bulb. Sanji(sp) has it rated as the highest par of any 175 watt bulb. The T5s are also the highest parblue bulbs according to grim reefer. but the best part of the par upgrade is the color. to me it looks better. less yellow. crisp blue/yellow.