I am trying to manage a pond used for swimming and fishing. I have taken over from someone who put too much copper sulfate in the pond. It is a 1.7 acre pond and I recently stocked it with fish after being told that copper sulfate is only harmful to fish when lots of algae gets killed at one time. Now many fish are dying and I think it's because of the toxicity of the high amount of copper that was used (120 lbs. over a 5 week period). If I test for copper in the water, what would be a safe amount to have present to be able to re-stock the pond? Or, how long would you guess I would have to wait till it would be safe for fish? I guess I will need to test for total alkalinity to get a picture of how toxic the copper is in our water. Thanks, Jeff