I have to agree with whiskers. I had a 1 1/2 acre pond with a weed problem. I bought 3 grass carp and 5 ducks. They cleaned it up and I didn't have to worry about using chemicals. It may take a little while but it works. Do NOT feed the ducks. They will start following you around looking for food, and it's hard to fish with ducks chasing your top water lure.x(

Steve