The ice on the pond must be kept open so that gases don't build
up during the winter. Only a small hole is needed, and we did not want to
use a floating heater. We purchased an aquarium air pump with 2 adjustable outputs on
it. We placed the pump in our garage to protect it and drilled 2
small holes in the garage wall. We ran some 1/4 inch PVC pipe from the
garage to our pond and pushed 2 pieces of aquarium air tubing thru the PVC
pipes with a large air stone attached to the end of each.
We are now able to prevent the surface from freezing in this area by the constant
motion of the bubbling air stones. With this type of air pump we can lower the air flow
when the weather is mild but increase the flow and create more motion on cold days when
freezing is more likely. Be sure not to place the air stones right near the pond
surface. The bubbles will create more motion if the stones are not deep in the water and
care must be taken not to disrupt the water temperature near the bottom where your fish
will be staying. Keep the air stones near the top so that the bubbles will
keep the surface moving.
DO NOT ever pound on the ice to break a hole open. The shock
waves from such pounding could injure the dormant fish. On those few occasions when severe
weather has frozen our pond above the bubbling air stones, we simply used hot water to
open the holes back up. Because of the air stones we use any ice that
forms in extremely cold temperatures is not very strong and easy to destroy
with just a small amount of hot water.