Right now the probe is held in place and can't be moved by Loki. The substrate is already thin and my temps are fine. I'm laying down cage carpet as her next substrate in the new tank so she wouldn't be able to move the probe in that tank either. I'm kinda concerned that the probe will hold the uth off the glass enough that it isn't heating efficiently, that's why I have had the probe inside. Is that not an issue for anybody else? If it helps,this is the thermostat I'm using

http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1