The pond was built in the 1970's. It was drained and redone in the 80's. Unfortunately I used clay but not bentonite which I think might have helped. A small stream runs into it. Also a mountain spring that feeds five cattle waterers, then the overflow comes into the pond via a pipe, about 12 gpm, all year round. We have lots of rain, snow in the winter thus the water level stays up. The pond is in the mountains of Virginia near the TN state line. I have used dye but it does not remain long. Should I use dye every two weeks as well? What do you suggest that is best for the algae treatment?