Yeah that's probably an 18" tall 55 gallon. Please tell me you have a THERMOSTAT that your UTH is regulated by, and not simply a THERMOMETER sitting on top of it measuring the temp. Do you have a mesh screen? Or simply an open top covered by aluminum foil? I ask because it looks like your lamp is clamped onto an open top. Dangerously high risk of escape! I'm guessing you turn that white lamp off at night allowing your temps to drop unsafely into the 70's. Those digital thermometer probes need to be on the floor of the cage. That is where the snake is so that is where you need to measure the temp.