Phaius Growing Medium

[Paerata]

Last November I purchased a Phaius from an orchid wholesaler who once a month allowed the public to come to visit and purchase. The Phaius is in a small 7 cm (3 inch)container being encouraged by the seller that it would fit in satistfactorily with the growing conditions of my half a dozen Phalas.
It is in a moss medium. Is it conducive to being put in bark, which is what my Phalas are in?
When should I repot it to something bigger?
It had 2 nodes one of which has died.