So, just to be clear, heat tape/UTH/heat cable is NOT going to increase your ambient temps by more than a degree or two, especially in a tub as enormous as 30-40 gallons. 41 quarts is the size I use for my full-grown females (2500g+), and many of them would be perfectly content in a 32-qt. as adults. If you have a hatchling, a tub that size could end up being a nightmare to clutter up enough for her to feel secure and to maintain proper temps in.