Originally Posted by
pastry
Kathy, I just started using some CRAZY submersible heater for my exterior 100g water aging tub. I'm in Charleston, SC. This is not an aquarium submersible heater... but it IS a submersible "type" of rapid water heater.
It was dirt cheap on Amazon. There's no control though. I just turn it in a few hours before a WC and it's heated up 60 degree water (without a tight fitting lid!) to over 80 degrees. Several times I've forgotten to turn off and after 3.5 hours it's been waaaaay over 80's (didn't do a reading... felt with hand and it was WAY obvious it was too high! Didn't take long for temp to drop while device was off).
It may take some trial & error on how to tie it into your stuff (maybe a separate container that has incoming and return water flow?), but TOTALLY cheap enough to be low risk purchase. Let me know if interested and I'll find a link. I'll provide even more personal observations (e.g., little sucker is 1500w)