You may be fighting a losing battle until you get the grass to grow around the pond. I'm also in NE Oklahoma and had the same problem. Used gypsum with not much luck and then alum with good results. But then after several rains, the water would cloud up again. I ended up spreading a very then layer of top soil all around the pond. It doesn't take much for the grass to grow in. I also put some sod down in the high runoff areas which helped.
If you haven't seen this link check it out. I found that the rates were on the safe side.
http://www.luresext.edu/aquaculture/clearingmuddyponds.htm
