I also use a small wally-world fan that I hung in my stand and pointed it over the sump. It comes on when my MH come on. I have 2 x 250w MH over a 144g and inside a canopy. I never go over 80 on the tank but we do keep our AC in the house at 73-74 F.
Like Ramsey mentioned...check your pumps. Also, is your AC cooling that area of the house. We literally have a couple ofdeadareasin our house that I would not consider putting a tank. Ok, not dead areas but hotter than normal areas.
Did someone say "DEAD"? (Have scalpel, will travel)