Talked to the Ag Extension guy today. He said, it's a real unique area of the state and 4 out of 5 tanks have trouble holding water. Said my best bet is to get a liner installed (but that's also the most expensive). Next option is to have bentonite trucked in (bags of it will not be enough, needs to be truck load). Cheapest option is to find some clay somewhere on our land to apply to the tank floor and sides.