Quote Originally Posted by SharkFan View Post
Thank you for the welcome and reply. The mat is an 8 watt and supposed to be good for 10-20 gallon tank. You are correct regarding the t stat bulb- it does create somewhat of a partial an air gap between the mat and glass.
Yea the one I have on my 20long is a 8 watt as well. Either your mat/thermostat is faulty, or that gap created by the probe is causing some issues. Before I swapped thermostats, it was a pretty sizable air pocket created by the probe and I had a really hard time doing anything with it. Putting duct tape all around the sides to hold it on well helped, but it didn't "fix" the issue. I swapped to Jumpstart thermostats not long after and that and their probes are a little smaller, that seemed to fix the issue. Not saying you need to buy new equipment, it just timed out where I was replacing things to try some new products out and that happened to solve the issue for me.