I hope this isn't against the rules, as its only semi pool related.
I have a lawn care company, and I am trying to heat a 2000gal water tank to around 80-90 F. This tank is kept inside, and water is drawn from it in 50gal-250gal at a time. The tank is filled by a 3/4 water line, with an automatic shut off when water level reaches the top.
My plan is to install an in line water heater on the tank fill, then use a recirculating pool heater pump to maintain the temperature. Heater would ideally be electric, as the tank is indoors. I'm hoping the whole system can be a "set it and forget it" type system that either turns the pump and heater on by a thermostat, or the pump runs indefinitely and the heater turns on by thermostat. The outside of the tank can be insulated to minimize heat loss, so I suspect I can get away with a smaller size heater. Is this possible with normal pool\spa equipment?