Hi Jeremy,
Unlikely. Stock heaters are designed
for watering tanks and do not have the punch to keep a 1500
gallon pond clear of ice. They also have a tendency to corrode
and short out in the middle of winter, electrocuting your
fish and blowing out your circuit breakers.
Mylar placed on the surface of the water
will simply be a matrix for the water to freeze onto, generating
an excellent seal over the water's surface and preventing
any gas exchange at all.
You are too close to the Arctic
Circle, Jeremy, and your plan is appropriate for, say, southern
Tennessee. A more appropriate solution would be either to
purchase a couple of Rubbermaid 250 gallon stock tanks from
your local Farm and Fleet, set up airstones and box filters
for both, using media from your pond's active filters and
moving your fish inside, or covering your pond with a poly
house or hoop-house arrangement. These are manufactured
as do-it-yourself kits by an outfit called Versa-Quonset.
A setup like this can keep the pond ice-free by adding a
small electric radiator under the plastic cover. It uses
air, nature's best insulator, to do the job.
