Yes, calcium carbonate, unlike most substances, tends to be more soluble
in cooler water. However, its not so soluble that cool water will
dissolve a toxic amount of calcium. I use oyster shell on calcium loving
paphs, even with my coconut chips. For some, like parvi's and brachy's,
I include large marble chunks at the bottom of the pot...hopefully
simulating a more natural situation where roots contact
limestone/marble/dolomite under the organic material..Take care, Eric
Muehlbauer...fanaticum opening while emersonii is taking its sweet time....