This last summer we set a record for the most 90deg plus days. I unplugged all heaters also I got a case of bottled waters. I then emptied some water from each one ( so they didnt blow up when I put them in the freezer). Then drop a couple into your tank, filter to cool down the water. Change them out as needed with frozen ones, refreeze the thawed ones, rinse repeat as needed. My tanks were swinging from 78 at night to mid to upper 80s during the day.