My bad. I'm using the Hydrofarm model with the thermostat probe attached to the flexwatt. My Accurite thermometer's probe was attached to the inside of the tub, on top of where the flexwatt sits. I also measured temperatures with my temp gun. I think I'll run a few tests with the thermostat and flexwatt over the rest of the day, and just increase the ambient temperature in the room with my snake's tub. Thanks for the advice so far!