Greg,

When we were in Miami, we used 1" black polypipe to make a solar heater.
It coiled on the roof and returned to the pond. The coils were flat on
the roof with a 2 x 4 and plummer's tape to keep them in place. The
pipe went back into the pond so there was a continuous column of water.
The filter ran it. The result was 88 degree winter water.

That was swimming pool water, so we had no growth of algae, etc. But,
check your regular pond piping....ours has only thin black coating on
the inside. I suspect yours would be similar.

The benefit of a small pipe and pond water would be low cost. The rolls
of pipe are cheap and the splices easy: inserts and hose clamps. OUrs
ran 6 years without a problem. We moved.

My concern for coils in BC would the freezes in the winter. It would be
hard to drain a coil. Might be that the coil would best be threaded
through holes in the 2 x 4 so that it could be removed and drained in
the fall.

You would probably want to monitor temp to see how the pond fares with
whatever rate of change you get. Afurther thought: how would hte plants
respond if the water were warm and the air cool? Probably irrelevant if
you are so shaded.

Good luck!

Jim

Greg Cooper wrote:
Ok I know that "Spring has sprung" and all - but my pond does get a lot
of shade and warms up slow.
I have wondered about the idea of a using solar heat from a roof top
collector to warm the pond to a better temp and extend the active season
for my finned friends. Not that I have actually done more than
thinking about it - living is coastal BC is about the worst place next
to Washington state for hours of sun shine anyway. But I thought if
nothing else maybe it would be an interesting thought experiment and who
knows maybe someone out there has tried it. I am thinking that one
would need a water/water heat exchanger because circulating pond water
up through a collector would grow algae and clog I am sure.
Crazy idea? what do people think?

Cheers.