I have used almost everything ..started out in a bark mix for phals, they did not do well ,switched to sphagnum moss, that worked really well..too expensive for a large collection though. Now I am growing semi hydro and most phals love it as do other genera, oncids, some slippers and even dends. I have mixed my own bark mix and find it works better as you can add things for more moisture or air around roots. We grow our phrags in what we call "barko". It is a bark mix in a semi hydro pot. Phrags love it..same principal as sitting in a saucer of water...only the saucer is built into the pot !!