Sorry to double post, but if you don't already know what ABG is, or for the benefit of others, ABG substrate is a mix of:
2 parts crushed tree fern
1 part peat (or coco fiber, but this is a modification)
1 part charcoal (crushed, something like aquarium gravel size)
1 part milled sphagnum
2 parts fine orchid bark
I tend to increase the ratio of charcoal to 2 parts as a personal preference, and decrease the amount of orchid bark arbitrarily.