If the heat pad is hot enough to heat the tank I would assume that it would be hot enough to use for a tub, but you have to make sure that it is properly controlled. Yes, you could use a soldering iron to melt, or drill, a hole large enough for your temperature probe to fit through, but I would put it in the side so the probe could stay in the tub when the lid is off. There are many good tubs out there. I really like Iris tubs, but I also use Sterilite.