If the water becomes warmer than 39 degrees, it will rise, and once the pond
is above 39, any cooling of the surface causes the water to sink until the
whole pond is 39 degrees and then there is no flow. If the winters are
extremely cold, and long, then the soil under the liner could be cooled to
below 39, but it will be getting heat from further down in the ground.
During this time, the bottom water will be below 39, but it will still be
the densest water in the pond and the circulation will cease. The shallower
the pond, the quicker the soil under the pond will cool, due to its closer
proximity to the cold source. For shallow ponds it could be possible that
the circulation is so little for so long that toxic gasses could become
saturated and oxygen not diffuse due to lack of currents and harm the fish,
I guess. The use of the air stone will cause a very slight turnover, with
almost no current and should be beneficial.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html
"~ jan JJsPond.us" wrote in message
...
Superkitt,
I'm a little concerned about your fish and plants being in the dark all
winter. I know submerged grasses, anacharis especially, don't respond well
to heavy shade, like my shade cloth, all winter.
Tom La Bron wrote:
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.
John replied (after heavy snipping)
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.
Here's something to discuss. I've always run my ponds so the bottom isn't
disturbed, but I did hear thru the koimag grapevine something about
shallow
ponds, less than 3+ feet, it 1) doesn't matter and 2) it isn't a good idea
to let fish sit in stagnant water all winter. Supposedly, (keep in mind
I'm
parroting for discussion) it is better to continue gentle flow off the
bottom.
In my case, that would mean when switching to my 300 gph pump in winter,
continuing to pull from both bottom drain and skimmer (making the skimmer
almost useless at that flow). I'm really thinking to stay with skimmer
only, especially with a spic & span bottom for the koi to sit on, but
another alternative would be an airstone on the bottom, something we're
always telling others not to do.
Some days this hobby is SO confusing. ~ jan
See my ponds thru the seasons and/or my filter design:
http://users.owt.com/jjspond/
~Keep 'em Defrosted~
Tri-Cities, WA Zone 7a
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