On Thu, 6 Mar 2014 15:34:45 +0000, Sacha
wrote:

In The Garden of Evening Mists, the woman learning from the Japanese
master is set to making balls out of copper strips. These are thrown
into the pond and sink. He tells her this is to deter algae. Has anyone
ever tried it and I wonder if it would work on the accursed duckweed?

I'm sure I have seen ponds and water features with copper coins thrown
in and still have algae floating in them, ok the copper comtent is
less than it used to be but there are a fair number of older ones
around.

G.Harman