The ragtop DIY tank was built on the bottom floor of an apartment. The floor had cold tiles. The tank was heated by an H2Pro submersible heater: you simply put the heating element in the water 3-4 feet away from the temperature probe and it would heat the water. This tank was super simple: just a plastic containment tank for the bottom and a tarp for the top. My guess is that neither the tank or the floor held much heat so there was never an accumulation of heat on the floor?

Now in my current build, the GIZA FLOAT TENT, I am experiencing extreme hot spots in the floor of the tank: the temperature probe (about 3 inches from the floor) will read 92 deg F but when I attempt to get into the tank, I simply cannot because numerous spots on the floor of the tank are red-hot. Now the suggested solution will probably work: circulate the water frequently.

But I have a question: why did my float-to-relax tank not need this sort of coddling? I did not run the pump regularly and in fact the system was missing a pump for weeks at a time. But there was never a problem with hotspots or ability to heat the water uniformly. I think a big part of the answer has to do with the long Aztec heating panels that spanned the length of the tank.