A sump might be a good idea but probably not till next season. My pond is too large to harvest by hand also. We are talking about way to many fish to harvest only need feeders plus we will be feeding mainly minnows. I have talked to people that have used the chemical aquathol and I believe it would nock my weeds out quickly. My next question is will they decompose over a winter or will my seine be so full of dead weeds when I harvest that I can't even pull it?