I have a new pacman frog, about 2 inches accross. I currently have an under tank heater to keep him warm, and it is currently glued to the bottom of the tank on the outside. Temp at the very bottom of the substrate on the glass is about 100 and at the top of the substrate (about 2 inches of substrate) the temp is around 85. Is this too hot? Would it be better to place the heater pad on the side of the tank? Thanks!