I think there, is one commercial mix, that may not be too bad, of quality ( considering what it is sold as & what is actually the ingredients.) Black Gold , may actually have pumice & sand, in it, here in U.S.
But I never bought a bag, although quickly read some of what was in it... I I did use that, I'd rather add coarse sand, more pumice, or perlite, to the mix, that would work best in my climate/conditions, for growing outside, spring through summer & into autumn & indoors, during winter.
Some growers in Europe, may still sell "cactus soil' such as possibly Kakteen Haage, which I think is an very old vendor, maybe in Germany but may offer it now, mainly just for starting cacti from seeds? While commercial growers have been known to simply use peat moss & perlite, compressed, to actually start the cacti seed, in greenhouse...
One of the problems, ends up, that the "mealy bugs' love to start to get into attacking the plants roots, when kept in that peat moss mix.
I started using nearly 95 % pumice, gravel, sand & /or with perlite, & sometimes added top dressing of some crushed slate, or marble, or fine righ gravel..to resolve that problem & simply watered, very frequently, with a little diluted fertilizer... Results; no mealy bugs, at all & much less tendency to rot.
I think it is better, to completely remove, as much as possible, near the start, of the growing season, remove it, after soaking & rinse it off & remove carefully as possible. Then allow to dry, ( without roots "stuck together") & repot, into a"dry mix" that you are going to use, so as to avoid the mealy bug problem & also avoid staying wet, for too long & rotting.
