on a whim, I looked up charcoal and found a site claiming it had nor more propeties than perlite.
Here is the site:
But the conclusion of this person is this:
In general charcoal should be thought of only as a substitute for perlite with identical value, not more not less. Like perlite it also functions to retain oxygen in the soil, so might be marginally better than vermiculite, which holds more water in the soil but less oxygen than either perlite or charcoal. As a porous potting soil ingredient charcoal needs to be mixed in thoroughly, & recommendations to use it as a surface layer or in the bottom of pots adds no actual benefit.
Kind of interesting. Of coure, there are more sites praising charcoal than knocking it.
How many of you use charcoal as a component of your Nepenthes mix?