The clay that is used is called bentonite or montmorillonite. It can be
dumped into the water to make a muddy mess, and some will settle out to the
bottom, but if there are any leaks, the leaking water will carry the clay to
the leak and plug it. Our Botanical gardens used it on a pond that they put
in and I think it took about 2 years for the water to clear, and then if you
have koi, they will root around in the clay and it will never clear.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html


"Mickey" wrote in message
...
Do some internet searching for something to put in the pond to slow the
leaks down. Maybe there is a clay or something that will suspend itself in
the water and clog the cracks up as it runs out the hole,
"Nicholas Walker" wrote in message
...
I've recently scooped out an old silted up pond in my garden which
filled
up
and overflowed every winter but dried out in the summer. It's a fairly
large triangle of about 20 yards each side. It takes four days to fill
with
a hose and then two days to drain. The clay base (of unknown thickness)
seems watertight, but I reckon it's leeching out where the clay meets
the
topsoil sides.

What are my options? It's a bit big for a liner but I understand that
the
clay could be extended up the sides. What is the technique for doing
this?
How thick does the layer of clay need to be? How do I test that the
clay
to
be used is up to the job?

Many thanks in anticipation