I have been having a hard time keeping my ball python's tank the right temperature. Currently it is an exoterra 18x36x12 tank with a zoo med heat under tank heater. Humidity at 55.... working on keeping it the right level with some tinfoil over the top screens. I have a zoomed thermostat but it just has a dial, no temperaure gauge, to keep the UTH on high or low. The junky thermometer I got from Petco says it is 65 F right now, but it is much warmer inside the hides.This has been happening since me and the roommates haven't been using the heat as much as it was getting too expensive. Should I get another UTH, or a heat lamp? How do I improve the temperature?