Hello! Donatello's tank is only 79 degrees max. I cant seem to get it warmer. I have a 100 watt bulb and 4-6" of substrate on 1 side and a screen on top of tank. Sometimes i turn on heating mat/ pad thats on the side of tank thats only 1-2" .Does anyone know how i can get it warmer. I dont have alot of money right now. The substrate/ bedding is zoo med forest floor cypress mulch.