Need advice on crushed oyster shell dressing for paph

[cnarciso]

Hello,

I posted something similar over in the paph section, but so far have had no nibbles, so I am going to start a similar thread here where there is more traffic and see if it fares better.

Recently (about 3 months ago) I got two new primary paph hybrids

Paph malipoense x Paph moquettianum
and
Paph concolor x Paph leucochilum

As all of the species involved in these hybrids are of the type that grow naturally on limestone I was wondering if anyone could give me any advice on supplementing calcium with crushed oyster shell. I have heard/read that topdressing with either crushed oyster shell or dolomite lime can help these plants considerably. Does anyone else use either lime or shell to supplement these type of plants? Or if you could just give me your thoughts on the use of lime/shell. I am basically just looking for confirmation on how much is a good amount to use for starters and if, in your opinion, it really does the plants much good at all.

PS. In case anyone needs to know, I grow my plants in an acidic bark mixture with some perlite and charcoal.

Thanks in advance!