I got my first arboreal a week ago and am following advice to keep the enclosure more humid. The spider seems pretty content and has already fed. For substrate I am using coconut coir with sphagnum moss on the top. I keep the sphagnum damp which means that the top layer of coir is also slightly damp. I also have a water dish in the enclosure. Unfortunately I am already seeing the development of mould where the coir is sitting against the glass. My wife, who is a gardener, says she won't use pure coir for potting plants as when wet it is great at encouraging mould. Does anyone else have this problem of mould in a humid terrarium? The terrarium is an exoterra nano tall, so there is plenty of ventilation. Is coir the wrong thing to use? Any advice?