Great advice, as usual, Meadowlark. Without going back to check, it seems like you wrote that the lime also helped to clear your ponds? My soil is heavy clay, which is great for sealing the pond, but it will stay muddy without some effort.
The oak trees are fairly large, perhaps 2.5 feet in diameter. Not sure if it is worth the effort. We have a nearly endless suppy of tractor tires, and they are more swimmer-friendly than a tree. Perhaps I will stick with them. Thanks much, Tom