I purchased a home with a 1acre 10' deep pond. During the summer I got watermeal bad totally covering it. I bought some Clipper and a surfactant and sprayed heavily. At the time I did not think I had any fish so I wasn't concerned of killing fish. I went thru 2 maybe 3lbs of Clipper and then put in aeration. I stocked some fish last year also. This year there are no signs of watermeal and I have caught some of the fish from last years stocking. I was told by some people this I was going to have to drain it to get rid of it. But I didn't need to.