Wow, thats a good price for the combo! I really like the Icecaps, but cost wise, I may go with the Aro MH ballast, which is what I have running (4) 110 T12VHOs right now. I'm concerned that it may be too much light. (2)x250=500w, (2)x110=220, 720w/90G=8w per gallon. tank is 24 inches tall, so I think it will be ok, but it would be nice to have y'alls input.