I used to use a sphagnum moss, perlite and charcoal mix for my phals but recently I've fallen in love with potting plants in semi hydroponics (s/h). They plants are potted into pre-soaked fired clay pellets that wick water up to the plant from a reservoir at the bottom of the pot. I find that it takes the guess work out of watering

. If you're interested, check out the semi hydro section of Orichid Board.
Good luck whatever mix you use

!
Ryan