Has anyone else had this problem? Last week I filled 4 water butts on my plot, they were all thoroughly cleaned beforehand, however, the 2 with lids are clear yet the 2 without are smothered in duckweed (I think thats what it is, thousands of small green platelets), does anyone know why this has happened and better still, how to get rid of it....there are no ponds or lakes nearby so where's it come from? ???
