How are you heating the tank and how are you measuring those temps? And is the 80* hot side, cool side, ambient? You should be providing your bp with a temp gradient if possible. It should be 90-92 on the warm side and 80-82 on the cool side. If 80 is your hot side, it's way too low. If 80 is the cool side, you're ok, but should have a hot spot to go along with that. If you don't have a thermostat, what are you heating with and how are you regulating the heat?