I spent this weekend trying to get my snake's new tub set up for her. I can't seem to get the temps right. The instructions that came with the thermostat are really not helping me (actually, they make me feel really stupid), so I really don't understand all of the options like "dif" and "sp" and all that. Maybe I set one of those options incorrectly. The set-up:

Tub is raised slightly above the ground by 2 wood stakes. 12" Flexwatt covers 1/3 - 1/2 of the 41 qt. tub's belly. It is attached with aluminum tape. This is plugged in to a Johnson's thermostat set to 103 degrees. Acurite measuring temps and humidity. Warm side is 86, cool side is 75, humidity is 70% (I know that's high and will be soldering more holes tonight).

What's up with the nearly 20 degree difference between the thermostat setting and the temperature reading? I've checked with 2 thermometers, so I'm pretty sure the readings are accurate. The temperatures in my room can very quite a bit, so I'm not sure how much that's affecting it. Should I insulate the tub some? With what? I currently have a blanket over it.

Thanks in advance for your help.