John I know nothing about grass carp except what I have read here on PBF. But from what I have read it seems the grass carp work slowly on the problem. So the inclination of pond owners is if they don't see immediate results, they think they need more grass carp. Then they put in too many and in a few years have a pond denuded of vegetation.
Ponds seem to be good (or at least persistent) teachers of patience.
I've put 4 in my old one acre pond as a preventative measure as I know Lilly pads and water primrose are just starting up again after the clean out. Hoping that four is just enough to keep the plants from getting too established but not so much it wipes them all out. Put a couple in my newish 3 acre pond also as a preventative. Don't know if that was the right thing to do or not but will see in a few years.
