What am I doing wrong?

I recently ordered a moss assortment online for my 20 gallon vivarium. On arrival, the moss looked pristine, but it’s been going downhill ever since. Can’t tell if I’m watering it too little? Too much? Some other factor?

The mosses pictured are sheet moss, mood moss, and a very sad, brown (I think) club moss.

I use distilled water only to mist (daily) and occasionally water (a couple times weekly). The humidity is consistently 80-90%. Despite all this, I notice that the moss feels mostly dry within a few hours of misting. I tried to remedy the situation by placing damp sphagnum under it, though I can’t tell if that’s helping.

The moss doesn’t receive much sunlight, but I compensate for this with an LED aquarium light. It provides the red and blue light needed for photosynthesis and doesn’t generate much heat.

What am I doing wrong?

by Buscards_Murrain