I have american pond weed and widgeon grass. The pond weed is growing in 4-5 feet of water and has spread over 75% of my 1 acre pond. Other than all the parts that stick up above the pond, it doesn't bothre me that much right now. Will be good for my fish to get established and survive until I want the predator fish to be able to eat them. Will the winter knock them down to where my grass carp can control them after winter? I would prefer the pond weed is gone after this year. I have 7 GC right now and they were anout 7 inches when I stocked them the first of May.