Yes I use limetone for this one the plant is not that big as I offered a division to a friend -- this clone is a pretty fast grower -- BUT the flowers does not open fully and I've also seen better color forms --this being said I'm pretty happy with it !!
How does yours do Ron? I was looking up some natural history on the web for this species. It normally grows attached to limestone rock (that may have moss and humus on it) on the forest floor (pretty shady actually). It can ramble around for 10's of feet, and periodically climb trees. Apparently it blooms pretty well on the ground, but poorly in the trees. This is another plant that I think may have a high phosphorus requirement.