Right now I have a 20 gallon tank for my corn. I am using a UTH for a 10-20 gallon tank. But the temp on the warm side is only about 77 degrees. This is measured from the side of the tank just off the floor. I haven't measured the temp of the substrate right on top of the Heater. My cool side is right at 70. Do I need more heat on the warm side and if so what is the best way to do it. I put a tree in the middle of the tank with a hide in the bottom of it for him to climb and go into. So far he is staying at the top of the tree wrapped up on a limb. I know it has to be between 77 and 70 up there. But he Isn't coming over to the warm side. I don't know if he isn't cold or he just doesn't want to leave the safety of his tree. I was using a tissue box in the middle of the tank for his hide. When it was in there he stayed in it all the time. Is this normal.