I'll state it more boldly: Oyster and egg shells in potting media provide essentially no additional calcium unless pH is far lower than healthy for most plants. Put your oyster shells in the attic with your humidity trays.
__________________ May the bridges I've burned light my way.
So how is this one doing for you, Ray? Still going strong? Have you experienced any "hiccups" over the last year with it? I have my very first Paph rothschildianum, so I'm interested in learning about any knowledge you may have gained since acquiring yours.
The only "hiccup" has been my wintertime culture - not enough light or humidity and inconsistent watering - but it's still around. Not much growth, but still around.