I went to a seminar here in central Texas sponsered by a local Biologist who is well known but I can not for the life of me remember his name, and he told us that if the wind is blowing hard enough to turn a windmill then it is putting enough oxygen in your water to start with. The point being is that all it takes is ripple action on the water to put the oxgen needed. Now if you are trying to pump something to the bottom that may be a different story.