I'm going to leave the fishes in the pond this year, as their indoor cousins
are maxing out my tanks.

So the plan is to leave the pump going beneath the surface (1') and put one
of the 100 watt heaters within a couple of feet of the pump. I'm also
tempted to cover the pond with 2" of stryofoam sandwhiched between a couple
of sheets of plywood. Perhaps paint the plywood black for the solar heating.

Opinions please.

BTW: I'm in zone 5b, pond is roughly 4x6 and 30" deep.