A lot of people have been having trouble with heat, myself included, from the heat wave across the US. I guess the same rules apply - if you have a hood, open it allow some air movement across it, and can also place a fan to blow across it so long as you realize there will be some water lost to evaporation. Zip lock bags with ice in will help cool down the water too. Ideally, less light should do it. I dropped my 55g FW
to 8 hours a day and the temp seems a little more stable. What lights are you actually running?