My 150 is set at 77, but actually got up to 79/80 during last week's heat wave, even with a 1/3 hp Current chiller. Unacceptable, I think! During last summer's long heat wave, my little 10 gallon nano, set up bare bones in the garage and filled only with zoos and softies, got up to 105 degrees F! Everything made it, believe it or not.