I bought a Zoo Med heat pad a few weeks ago and it got entirely too hot. Temp was at 111 to 112 degrees. It didn't have a thermostat so I went and bought a rheostat and have it set on as low as it will go without shutting it off completely. Problem is the temps sometimes still get to 108. I felt the substrate (cypress) to see how warm and it doesn't feel 108 but who knows. Is this normal with zoo meds or is this a defect in this one? Any help is appreciated. Thanks in advance.