My wife an I are closing on our dream property the end of July. 23 acres with a 1.8 acre spring fed pond. The current owner has a pond aeration windmill. I had never heard of this before, but think is pretty cool. Unfortunately, believe it or not, the seller is taking it with him. Apparently it was an anniversary gift given to him and his deceased wife! At least that is the story I am being told.
Having said that I need to purchase a new one. I have been reading as much as I can, but still can't make up my mind which brand to purchase. The location of the current windmill is about 100' away from the pond on top of a hill. No obstructions. I have been focused on American Eagle and Koenders.
From what I can tell the American Eagle needs to be greased every year. How the heck am I going to get to the top to do that, if I can't climb it. It does not appear that is the case with the Koenders. Another concern of mine is freezing lines. The Koenders requires an anti freezing kit, the American Eagle does not. Any help would be appreciated!

Is the pond too far to run electric or an air line from a building with electric?

If you really want to aerate, purchase an air pump and run a poly air line from the house to the pond. Windmill aeration is too sporadic in most areas to do much good, especially at night.

I think you could purchase a real aerator pump and run an air line a considerable distance for the cost of a windmill.

I have both brands of windmill and, as of last year, another system running off of solar. I have posted a few times about what I think of each unit. I have also posted a few times about the complications of long distance runs of airline. You should be able to search my posts.

IF you decide to go with a windmill I would have to choose the Eagle. IF you go with either windmill a hinge kit so you can tilt it down for maintenance is an absolute must have!!

Only one windmill in a 1.8 acre pond will not adequately mix that size of pond. At the very best one windmill mixes acceptable amount for 0.5-0.7 ac. From my limited experience with spring fed ponds they rarely winter kill which depends a lot on amount or volume of flow from the spring to reduce water retention time.