On Fri, 02 Jun 2006 21:10:58 GMT, "Snooze" wrote:

Has anyone here had much experience with using oyster shells to provide
calcium for aquatic crustaceans and to buffer pond pH? Primarily any
difficulties with general hardness because of the extra calcium? Obviously
I'll have to keep a closer eye on the pH now, and possibly deal with calcium
buildup at the waterline.

Otherwise any other suggestions?

I use garden lime because it is cheap and available, but the KH stays
very low and the pH usually stays around 7.8 to 8.2. After a rain
the KH will sometimes drop so low it is a bit frightening, but when
the pH drops below 7.8 the lime begins to dissolve raising the KH and
pH. I suppose the oyster shells would react about the same.
General Hardness has never been very high. I used plaster of Paris
to raise the GH several times, but it never seems to make any
difference to the fish that I can see, so I have grown lazy and ignore
it.

Regards,

Hal