This is my first time with kingsnakes, although I've been successful previously with pythons. Here's my question. I have a Herpstat thermostat set at 82 degrees; the thermostst probe is set on top of a piece of 11" heat tape that covers a good portion of the bottom of a styrofoam box. Water bottles are on the bottom of the box to spread the heat and a piece of egg crate is on top of the water bottles to hold the egg containers.
As indicated, my thermostat is set at 82 degrees, however the thermometer I have inside the incubator registers 75 - 76 degrees. Which is the more accurate, the thermostat or the thermometer? All suggestions and advice are welcomed.

Thanks,
James