Jimmy,

Go get a water sample and let it sit in for a week. If the water clears up something in the pond is making it muddy. If the water does not clear up you probably have an ionic balance that is keeping the clay from settling out.

Alum and Gypsum work really well to clear muddy water. Alum will drop the pH so you have to buffer it with hydrated lime.

Gypsum is safe but you have to use high quantities. I'm working on getting some gypsum rock for my pond. You can just throw it in the pond and it does the work itself.