last year I was hanging up a few 2x2's in the terrarium so I could hang a couple of neps from the top, where it's warmer closer to the light. Because of weight and I got a go at a little experiment, I repotted a 15 cm diameter truncata in pure perlite to see what would happen. The first thing that cought my eye was the build-up of calcium on top of the perlite, I often get a bit of calcium in the water and have to replant most plants every 2 or 3 years. But with the plant potted in perlite, I can simply scrape of the top layer and replace it with fresh perlite.
The second thing I noticed was a normal evolution in growth. What ... normal ? Yes normal, not stunted or better, and we're almost a year further now.
So I started wondering, is this a lucky shot or are N. truncata not really that dependant on organic matter in their soil ? Has anybody tried this with other species ?