Pond Boss Forums MANAGING AN EXISTING POND Fertilization Stop Fertilizing due to FA?

I'm with you on the copper sulfate. I can't remember where I read it, but there have been studies done that show it can build up in a pond if used multiple times, and can harm the fish; it's not a great leap of imagination to think that such an effect on the fish would likewise not produce a great effect on anyone who ate the fish.