Back to your original topic SP!
I finally took the plunge today and repotted an orchid into lava rock.
This is one of the very first orchids I bought (NOID Phal) and I've wanted to repot for about 6 months but there had been no sign of new roots so I'd held off. I repotted into bark soon after I bought it 2-3 years ago but last year it developed crown rot and I thought I'd lost it. Happily it put out another basal growth that has grown very vigorously and I've just been waiting on some new root growth. 2 recent soaks in Kelpak did the job.
I took the existing root ball out of the pot and started removing loose bits of bark and then discovered why the roots hadn't been too happy. It still had the original plug of compressed moss in the middle! I can only guess that I originally repotted it before I read all of 'Phal abuse stops here'!
Anyway, got rid of all the broken down media and gave it a good soak in Kelpak and repotted in a terracotta pot using the lava rock. It was easier than I had expected to work with. The plant had got very top heavy in it's plastic pot and feels so much more secure now. I've left it to rest/dry out any damage to roots overnight and then I'll water with Kelpak in the morning and fingers crossed!
It hasn't started a new flower spike yet this year but there are 4 new branches on old spikes so I'm hoping for some bloom soon if it hasn't got too stressed.