Dennis,

Limestone will not hurt the fish. If the water is in contact with the
limestone, it can, though ever so slowly, dissolve into the water. This
will help maintain a good pH, since as the water becomes more acid, it
dissolves faster. Some of us put oyster shells in the water to do the same
thing.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html


"Dennis" wrote in message
m...
We are thinking of capping our new formal pond with those 2" thick
smooth slabs of limestone (with the rough outside surface) that are
available at most local block dealers. Does anyone know if these
could be harmful to koi, comets or orfe?
Thanks
Dennis