In message , ned
writes
DaveDay34 wrote:
For a pond to be effected by
'layers' in the winter it's probably going to need to be in the in
the region of about 100ft + deep. For a 3ft deep pond the water
surface temp will be the same as the bottom temp whether the pump
is
running or not.


No it won't. If it was, ice would form at the bottom of 3' deep
ponds. As it is ice is less dense than the water at the bottom of
the pond (which is densest at 4 degrees centigrade) and so forms on
the surface of the water/pond.

Pumps should be turned off over winter, and ice which forms on the
surface of a pond should be melted to allow the escape of toxic
gasses that can build up over time. Breaking the ice using physical
force can injure the fish in the pond.


My pump runs 24/365. The running water ensures open water at the
inflow during freeze conditions. And my fish survive - to my
knowledge, for twelve years they have survived.
Oh, I *will* endorse the warning about not physically breaking surface
ice. Quite right, sir ...... although I've never faced the need.

where in the UK are you Ned / DaveDay ?
--
dave @ stejonda

calculate your ecological footprint http://www.lead.org/leadnet/footprint/