I just had my windmill installed recently, so I can't tell you the results so far. But, it does pump oxyegen more times than not since my pond is in the middle of a field and no trees nearby to block wind from any direction. I believe that is a key factor. I also noticed, quite happily, that it doesn't really take that much wind to generate the pump and see a boil from your diffuser. A breeze will get it going. The other good thjing I did was to but a Vertex CoActive air station from Ted Lea and Forevergreen (see post above) So far, it readily accept the air fro the diaphragm pump and creates a much better infusion of oxygen that the stone diffuser supplied by Koenders.
I had my windmill built, erected and secured by a friend of mine who sells Koenders windmills on behalf of Joe Mescan, along with two Amish fellows who helped him. For $300, it was well worth it.
So far, I really like the windmill, hope it produces some beneficial results over doing nothing at all (I, too agree that wind action alone does not supply oxygen to the bottom layers of a pond more than 6' deep), and it adds an aesthetic appeal to the pond. If you don't want an electric bill or have to bury tubing for 500', it may be worth the investment. Nothing beats an electric compressor setup, but you got to make a choice based on what's good for you.
