I'm really struggling to set up my tank. Right now my tank is the ideal temp on both sides according to my thermometer on the hot and cool side but the temp gun says something different. When I point it at the tank it says about 80 and if I put it in the tank it reads 104. Am I using the temp gun right? Should i point it outside of the tank through the glass or put it in the tank and point? Should I trust the thermometer or the temp gun? Also I have a probe for the Under the tank heater but I'm not sure where to put it. I heard mix reviews on where to put the probe. I heard in the tank under the substrate so it sits right above the tank but I also heard outside the tank under the heater. Please help