miya lijin - copper sulfate is a heavy metal based chemical. Once in the pond the metal is bound to sediments and it never deteriorates and never goes away. Thus it accumulates in the sediments after each use. Lots of Copper in the sediments becomes toxic to the organisms that live in the sediments. I think coppersulfate is bad for the long term ecology and health of the pond. What happens when sediments are toxic after long term use? USEPA considers coppersulfate a hazardous chemical. Can the pond owner sue your company for ecological damages?