Also a good option essup. I had thought of those that place small fish tank aerators near their dock piers to keep them from locking into the ice through the winter. Unfortunately, I am not able to aerate due to the fact that I have a closed loop geothermal system sunk into the bottom of my pond.

In my case, I figure the siphon system won't displace enough water to make much of a temperature difference on the bottom. I would love to aerate, but I'm afraid of what might happen to the thermodynamics that are required for our system to function at the proper efficiencies.