In article , TJolly.1udk81
@gardenbanter.co.uk says...


Is their any chemical you can purchase that can completely get rid of
it?


Roundup will kill the duckweed but also any other plant it touches. And
no, it wont kill the fish!
A friend called in the environment agency to help him clear weed from a
fishing lake, the advice was 'roundup'. It apparently goes straight
through without causing any damage.