A pH of 10+ in the Ozarks is rare! Usually pH runs in the low 6 range due to pine, cedar, and generally infertile soils. Limestone can't raise pH beyond 8.4 for Calcite, and again, most of the Ozarks is Dolomite limestone, that max's out at 8.2. I am wondering what is causing the high pH. Fish poo and leaf litter may eventually lower the pH some, but not for years to come. Does the happen to be a lot of algal growth in the water? FWIW, I don't concern myself as with what the pH is, but more with the hardness and alkalinity. If both hardness and alkalinity are calcium carbonate driven, pH will always be around the upper 7 to very low 8 range....Several gallons of Muriatic acid, or about 200 pounds per acre foot of Aluminum Sulfate will lower pH...I don't know for how long though.