I'm dealing with this problem right now in central cali. Going to be 108F all week. Problem is my 200 gallon is in the garage. Been using 4 frozen 2 liters, 4 frozen large Gatorade bottles, and 6 frozen small Gatorade bottles. Along with 2 large fans(one pointed at the surface of the main tank and one at the sump). Been able to keep 78F- 82F. Quite a lot of work. I am also getting up to 5 gallons of evaporation every week, so adding treated ice water helps as well.