Sandy,
Here in northeast PA there there is a good size pond down the road that the owner aerates all year. He has to have a pretty big air pump and substantial piping because he has three areas he bubbles. Keeps the water oxygenated for the fish and ice free for the ducks. You could do the same on a smaller scale. Not sure if he does any filtration but I suspect not. Been doing it for years so the system works.
Al