How to control Duckweed
There are 3 types of Duckweed in North America. There is Common Duckweed, Giant Duckweed and Dotted Duckweed. All duckweed grows in ponds, lakes and streams. Duckweed grows in dense groups in quiet still water, and usually there is more than one type of duckweed living in the water. All duckweed is aggressive inhabitant in ponds and if left untreated, can cover the surface of the pond quickly. This will cause depletion of oxygen and possibly cause fish kills. Ducks do eat duckweed and often transport it to other ponds and lakes, so it is important to get it under control quickly.
Duckweed and many other aquatic weeds flourish in stagnant water. So the best way to keep this under control is to install a pond aerator, whether a sub-surface or decorative pond aerator, it will move the water around an put oxygen back into the pond, disrupting the ideal environment for the duckweed. The aerator will push the duckweed closer to shore and makes the removal much easier.