Potting Media For Thin Roots

[Kaity]

I am working on a terrarium and want to have a layer of potting media to plant my mini Pleuros in. I was looking at the seedling mix for REPOTME.COM and it has very small bark bits and charcoal recommended for tiny roots. Only problem is..it's expensive. Can I just use the regular size orchid bark from the local nursery? Mix in some sphagnum, and charcoal? What do you recommend?

[smartie2000]

I don't grow lots of Pleuros. My advice is that straight sphag moss would work with most orchids with fine roots