I have 2x250s on my 110 and all I have is 2x6" fans from wal-mart, the clip-on kind. I am in Oklahoma and it stays about 90-105 in the summer months. Keep the house at 75 with the fans and eveything if good. I know I have a considerable more amount of water, but if you have a sump and overflow for water to pass by, with a fan blowing across the sump too, then I think you would be ok. 8 fans is alot, my gf's tank doesn't have any yet and it doesn't get too hot. Also I am with him 8" is plenty for the lights above the water. Do you have a sump?