So far, I have not seen a sign of duckweed returning and it has been close to a year I think? I don't have any vegetation growing from the bank at the moment. The only problem I have now is some muddy water from all the recent rains but that usually clears up. Keeping my fingers crossed for good luck!
Jay, in my limited experience, duckweed remains a problem until you get a mat of vegetation growing out from the bank. You'll still have duckweed but it will be locked up in the vegetation instead of freely drifting around the pond.
