Alum (aluminun sulfate) will definitely work. The problem is it is very expensive to use on large bodies of water. It can also kill fish if the dosage is to high. The problem I have with alum is that one side of our lake averages about 3.5' deep and suspended silty clay particles that will not settle out. We know alum will settle them to the bottom, but I don't believe they will stay there because of wind/rain/wave action. After a while of calmness they may settle again, or may not???
