billewing :

I don't know about your pond goals but duckweed is not in mine. It covers the entire surface unless it is constantly removed or treated as stated/implied in the posts above. It shades out everything including the plankton which is the base of the food chain in our ponds. It is also very hard to fish in or through. While it may be worse under fertile conditions it will grow in infertile {not fertilized} conditions , like very clear tanic water swamps. I will not let it grow in our ponds , it comes out asap. ewest