I have an approximately 1/4 acre pond that does not have fish in it. It is overcome with weeds. You name it, I probably have it. Duckweed, Cattails, water buttercup, algae, emersed, submersed, floating--it's really bad. I know you can't use Round-Up, but what is effective? I've been told copper sulfate by some, Weedtrine-D by some, Glyphosate by some. Is it possible that I can get it cleared out this season?