Human heating pads are not made to heat tanks or tubs with snakes in themyou need to either get a precut UTH (under the tub heater) or flexwatt. You also need a thermostat to control them & a digital thermometer to monitor the UTH. There are many threads in the forums on this site to guide you according to your budget. With a glass tub you also need to make sure your humidity is 50%-60% most of the time and 70-89% when your snake is in shed. A wet towel on top od your screened lid helps with that. Good luck and have fun.