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29-10-2002, 03:00 PM

in article , DaveDay34 at
wrote on 28/10/02 4:32 PM:

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.

I hope that this clears a couple of points up.

Dave.

Dave,

If it's say January / February. The pond is 3ft deep and is unfrozen at the
surface. Do you expect there to be a difference in the temp from the top 6
or 12 inches to the bottom at 3ft.

From past experiences I'd be very surprised if there were. The reason being
that as well as being interested in gardening & ponds etc.. I'm also a diver
and continue diving throughout the winter (in inland lakes). During the
winter months (Dec, Jan, Feb, March). During this time the surface water
temp remains the same as what it is at 22mtrs (usually around 3 or 4 deg c)
It's not until you drop down to about 30 - 36 mtrs that it 'warms up' to
about 9 deg which from my records seems to be the constant year round temp
for this depth.

Hence my reasoning that 3ft just isn't enough depth for a difference to be
noticed from the surface.

I do agree about breaking the ice though. Although as someone else has
mentioned, you don't have to break it if the pump is still running as the
movement of water keeps it from freezing.

Regards, Ian.