Bob Hobden wrote:


"Sacha" wrote...
"Bob Hobden" said:
Don't forget water too, most of it out there is frozen solid and the
birds need to find some to drink. They use the filter outfall into
our pond which always stays unfrozen.

Bob, we stop the pumps running in winter on the grounds that it makes
the water colder if it's being recirculated. I think that's the
reason anyway! Presumably you don't go along with this theory?

It may do but the pump produces some heat to compensate and it's never a
good idea turning off a biological filter, especially a large one. All
the bacteria will die or be replaced with anaerobic types so when you
turn the filter back on you next spring you will effectively push the
muck/toxins back into your pond, bad idea.
The only recourse if turning it off is to strip the filter down and
clean it thoroughly leaving it dry and start again from scratch in the
spring but then it will take months to build up its bacteria to full
strength. That said you can purchase biological starters for them in
bottles.

If it's a sand filter the organisms within are algae, and will be quite
OK so long as they are kept wet.

Even if they do die, a fortnight's running will 'seed' it with freh algae.

--
Rusty