I just have never been a fan of chemicals. I think they should be the last resort. We grow our own hay for the horses, you would not believe some of the hold times for forage consumption when chemicals are involved. I often wonder, that in a closed system like a pond, where do all of those chemicals utimately end up. It may be nothing to worry about, it is just my opinion. I am glad you mentioned about the mechanical removal. It would figure,that was going to be my approach.

Ron