I don't know what sort of fixture you have on the tank but hopefully it has some good fans built in. You can also place a fan somewhere near the tank to blow across the fixture. The higher it is raised from your tank the better. You don't really want cf's sitting directly on top of most tanks(like you said already).
You said that you have air circulation inside of the tank which is good. Is your tank sealed off? The greenhouse effect starts to take hold with higher lighting methods.
My apartment is at the top of a house so it gets somewhat hot during the summer. 78 or so with the air running all of the time....70 or so during the night. My 40 breeder has a coralife 192watt fixture that sits about 3 inches above the glass. I also have a computer fan that pulls air from a spot on the other side of the tank. I think the main temp reducer for me is the water feature. It gets around 84 during the day and 72 during the night.
Good luck,
-Andy
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