"SA" wrote in message
news:PRJxc.308$tY1.268@newsfe2-win...
Think I heard that you get some barley straw in a fine net bag and weight
it
to be just under the surface.

Don't think that has any effect on duckweed, however it can help to clean
green water.

--
Brian
"I know about kittens and knitting. Will that do?"