These started appearing in my 8ftx4ft 20 year old pond last year, they float and have a 2cm root as thin as a human hair. They cover the entire surface of he pond. I scoop most of them out with a small fishing net, and before I know it the pond is covered again. The plant in the pond have been there for over 15 years. Where on earth do they come from and how do they spread. It is as though someone is sprinkling them over the pond that spread so fast. The big question - How do I get rid of them.
The picture is of the waterfall header.