So I hooked up the home water heater to heat the saltwater system! It’s all controlled by the ReefPi. It works very well and is holding the tanks between 78-79 degrees F.
Radiant heating is a great solution using a hot water heater. I used it on my last system and already have it hooked up on my new system that I am building. Did you keep a water tank drain valve in line? What kind of pump are you using for recirculation of the heating loop?
The tank drain valve is hooked up with a hose bib to copper connection so it can be serviced. The pump is a two gpm Recirculation pump made for hot water heaters. I got it on Amazon for around $25.