My pond is covered and heated during the winter. The cover is a lean-to
with 3 layers of poly sheeting and one layer of the pool solar cover. I do
not leave a venting area around the perimeter, but do enter the enclosure 2
times a day for feeding the fish. I do not think it would be necessary to
provide any ventilation if the cover is mounted above the pond. If it is
layed on the surface of the water, then I would leave at least an inch all
the way around and install airstones. The water will not be able to have
gas exchange under the cover, and will get fouled.
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RichToyBox
http://www.geocities.com/richtoybox/pondintro.html
"MC" wrote in message
om...
I plan on covering my pond (zone 5, Chicago) this winter with a solar
pool cover (it looks like bubblewrap). The question is how much area
do I need to leave open for gases to escape? If I leave 1" around the
whole pond, is that enough?