Karin,

In Sept and Oct I had a difficult time keeping the temp down, (FYI...we keep our A/c around 74 degrees throughout the day), but I played with the timer on the PC lights and I vented the top open about 4" to help heat escape...I currently turn the lights on at 1pm to 8pm, but they are next to the kitchen/breakfast area so they get good natural light throughout the day. I think venting the top was the biggest help as it dropped the tank more than 2 degrees.

MH