Be careful of the metal in the heat exchanger. For swimming pools, I think
they use copper. Copper is the best at heat transmission. But copper is
toxic to fish. Use titanium or stainless steel heat exchangers. I know
several that have used natural gas and one that used propane. The one using
the propane stopped mid season due to cost, but he didn't cover his pond
either. I would recommend building some form of cover over the pond, tent,
lean-to, hoop house, greenhouse, or something to insulate the pond from the
cold and wind. Hot ponds cause steam to rise off the surface and that is
evaporation, and evaporation is on of the best forms of refrigeration that
you can find, so not having a cover causes serious heat loss.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html


"Dennis" wrote in message
m...
Has anyone ever used a swimming pool (propane) heater for a koi pond?
Can you see any problems with using one? I am trying to heat 10,000
gallons.
Thanks
Dennis