Brian from Mtairy, Maryland writes
I live in Maryland and last year our pond was covered with duckweed and water meal.
Aquatic herbicides like Clipper SC Aquatic Herbicide are used only to kill what is growing. They will not prevent anything. You should start applications as soon as you see these weeds for best results since they can multiply very rapidly. Usually the water will need to be at least 55-60 degrees consistently for these weeds to thrive. We have a guide here that might help.
Answer last updated on: 04/05/2021