Yes sir I amYour not talking about a tankless water heater for a home are you ?
heard a few storys how people of had there water heaters break open and fry there fish. Was thinking what if you could heat the glass from outside of the tank to warm the water.
I have seen them in use in bigger multi systems an fish pondsYes sir I am
http://www.marinedepot.com/ps_viewi...fa8iWHWiKB8KvULo8qrs9416a535eOtUicaAsPN8P8HAQ
When I had tropical fish in my 125, I used one of these on the return for each of my 3 filters. Just for redundancy
There are diy versions but by the time you buy the a good heater. I would spend $5 more and get this
I raised my fish tank room to 78 and ditched all the heaters. Got rid of the weakest link.With gas so cheap this year, I raised the temperature of my house from my usual 68 to 72. Keeps the individual tank heaters from running as much.