This might sound crazy to some, but I have been growing mine ( Eumelia arias) in fine podwer like form of coconut husk with a saucer filled with water for past few months.
It is very happy.
it will be interesting to see how they do over a long period of time. Coconut doesn't break down as quickly as sphag, but it does pack down. I mix coconut chips with perlite for most of my orchids and it works very well.
I had it in that mix for nearly one year and it went from 5 to 11 fans. lol
I bought the plant as a bare root, and I didn't not have any good potting mix handy. so I just bought this cheap coir brick from a store nearby as a quick fix.
I meant to repot it into something more open as I was worried the roots might die out in this mix, but I'm surprised myself.
I think it makes sense. Most of these plants grow in places that drown them, i.e. they grow in 'muddy' conditions with flowing water. I think as long as it stays fresh it's a great idea! I might try it with one of mine.
I potted up three expensive paphs bought at the same time in the same mix, but they didn't seem to like it much and they were expensive (this phrag was only about $30), so I switched them over to bark chips in the summer. so glad I did. Two of them are spiking now, and one is still half dead. lol
This thing was doing fine, so I just left it in the "mud". I see one of the fan is starting to get really big so maybe I will see some flowers in the new year.