Rick, it is grown in charcoal, limestone and moss. No particular ratio, about equal volumes of each. When I got it, it was grown in floral foam cubes, small granite rock and cocopeat a tray half filled with water. Amazingly in such a system, roots were very good. I think bellatulum really enjoys wet roots (with good aeration), but not wet leaves..
That is a very shapely bella! Great petals and attractive spotting. I am going to try your mix on my bellas and see if they grow any better. I can fill a whole page on the 'paphs that you have killed' thread on bellas alone!