Following this thread a bit more, if you look at borneo exotics website on nepenthes mixes, it is claimed that if you use perlite in the mix, when it gets too old, it breaks down and release fluoride which is harmful to your neps.
If i am not mistaken, Rob grows his plants in charcoal and coconut fiber. His plants look great!!!
Yeah, I have heard that a lot. Our tap water here is high in flouride, which is great for teeth, but not for plants. I would think the flouride has to come from somewhere to get in there.