"drsolo" wrote:

get some limestone pavers and put them in your pond. they will dissolve
slowly and add calcium to the pond. Ingrid

If you have a liner, you need to be careful with the pavers since they
are heavy and have sharp edges. The most gentler way is with limestone
river rock. They are rounded but more difficult to clean around.
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18,000 gallon (17'x 47'x 2-4') lily pond garden in Zone 6
Cheers, Steve Henning in Reading, PA USA