hello! i have two whites’ tree frogs that have been getting a little chilly at night, so i purchased a “rainforest” exo terra heating pad to attach to the tall tank in the hopes that it will improve nighttime temperatures (i will put it on a timer). what i am unsure about is whether i should mount the pad to the raised bottom of the vivarium under the moist substrate, or on the outside of the back wall behind a 1.5 inch thick styrofoam background. i am leaning towards putting it on the ground to heat a portion of the substrate because it might damage the styrofoam and not pass through it to the inside of the tank if i was to put it on the wall. is this a good idea? is there anything else i should know about heating pads? thanks!