i say 250... i think anything less is a wast of $$... i mean.. with a 175 you cant really do much but with a 250 you can do a lot more.. ( it lets you go the the 24'' hight ) anything less you can do better w/ other lighting set-ups ... ( t5,pc's) i think you should be fine w/a 250.. worst to worst, you can just raise the light u[ higher... ( more is better than not enough)
YzGyz