On 2014-03-07 08:13:06 +0000, Chris Hogg said:

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?

A strip of bare copper wire along the ridge of a house roof is
supposed to keep the roof clear of moss. I'm not quite sure what form
of life moss is, but copper is poisonous to many life forms (eg it's a
popular fungicide, and above a certain concentration can inhibit plant
growth) so it wouldn't surprise me if it prevented algal growth in
ponds. But it raises the question as to what else it would kill,
animal and vegetable. You might end up with a sterile pond.
Controlling algae is better done by controlling the nitrate levels in
the pond by not (over)feeding the fish. Duckweed may be similarly
controlled. If the fish aren't fed, the nitrate levels in the water
will be low so won't encourage the DW, and the hungry fish will eat
what's remaining. No DW or algae problems in my pond.

If we don't feed our fish, they eat the frog spawn. ;-( We're feeding
lightly now.
--

Sacha
www.hillhousenursery.com
South Devon
www.helpforheroes.org.uk