Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations Bass Dying all of a sudden

Not an expert, but agree with JEC on timing.

I also seem to recall some threads about submerged plants developing "seeds" that are subsequently spread around the pond. I suspect the best time to treat those types of plants is right before full seed out. The plant has exerted lots of its energy reserves and you can kill it BEFORE the seeds spread.