Hey man till you ca get the tank moved get a small fan and have it turn on during the hottest part of the day or when the lights are on. Just have it blow across the top of the tank. They really do work. it is always cheaper to have the heater turn on then to have everything die. When I had my 10 gallon up with a 150 watt MH on it all I did was get a small fan from wally world and it kept the tank at 79 all the time. It will help. Also the tank is looking good. I love the aquascape. With the powerhead. Get some foam. If you go to any LFS or Petstore get the foam inserts that go in the AquaClear filters. Make a small cut in one end ad slide the foam over the intake.