On Sat, 4 Oct 2003 08:04:43 -0500, "Tom La Bron"
wrote:

Superkitt,

Where is the second pump that you left running drawing its water from? If
it is at the deepest part of the pond you should position it in an area
where the water is shallower. The fish will congregate where the water is
deepest and you do not want to pulling the water from the deepest part of
your pond. You want to leave this area pretty much undisturbed to allow the
water to absorb heat from the ground. If you are constantly pulling water
from the deepest part of the pond you will effect a cooling in that area
making it harder for your fish to sustain their body fat for the winter do
to increased swimming activity. It is a good idea to raise the pump off the
bottom, but leaving it in an area where there is less chance of it freezing
in the ice.

In any event, the whole idea is to leave the water in the deepest part of
the pond where the fish will stay undisturbed by water movement, so it will
absorb warmth from the ground.


Is that really true? I do not know the answer but what I do know
causes me to question your theory.

The reason I question it is that water has the very unusual
characteristic of being most dense at 39 degrees F. At temperaturs
above and below that it is less dense. Therefore, if there were no
flow induced by pumps, streams, etc. the water at the bottom of the
pond would be 39 degees F as long as the ground temperature was not
higher than that. If the ground temperature is higher then it does
not matter what you do.

If the ground temperature would get lower than 39 F, as it would in my
section of New Hampshire, then it seems to me that settling of the
dense 39 degree water into the deepest part actually keeps the ground
from freezing.

If that is so, then eventually the water will lose it's heat and
everything freezes. But, there are many days in which the air
temperature is above freezing. That warms the water to it's densest
point (39 F) and actually results in a warm flow from top to bottom.

I guess that now that I have written this and thought it through, you
are correct, the best policy is to leave the deep water alone. A
happy circumstance, being right even if for the wrong reason.

Does anyone see any flaws in the above. I would like to understand
the physics so I can operate my pond properly.

John