"Kev" wrote in message
...

She still wants to heat the new pond to some degree. question, on a sunken
pond is there any standard way of trying to minimise heat loss through
design / construction of the pond?

Your views appreciated.

Kev (and Julia)

You don't say where you are located or what depth the ground will freeze in
your area, so I will give my general feelings. I have two ponds, one 4000
gallons and one 3500 gallons that are both heated to around 70F (20C). The
most important thing that you can do to heat a pond is to put some type of a
cover on it to minimize evaporation. Evaporation really cools the pond. I
cover mine with a lean-to structure that can be seen at
http://www.geocities.com/richtoybox/pondpage3.html. This structure gets
covered with a solar swimming pool blanket that looks like bubblewrap and
two layers of polyethylene sheeting. It accumulates some solar heating and
helps retain the heat in the pond. The earth at a couple feet below the
frost line is pretty constant temperature around 50 degrees F (10C). This
relatively warm earth will act as a heat source if the pond temperature
falls to below this temperature, so I don't like to see it insulated. The
walls of the pond, near the surface might benefit from some insulation,
since the frozen soil would rob more heat from the pond.