Do you have the UTH and the CHE running off the same thermostat?

I would place the probe between the tank and UTH. Your temps would be more stable. Of course you'd have to have a digital thermometer to make sure that your temps are in the right ranges. You don't want too many external sources to influence the probe.

Here's another thread that may help ya too. http://www.ball-pythons.net/forums/s...ad.php?t=27796