I was using about 3 inches of organic potting soil in a 32 oz cup for my L3 nymphs. I thought it would help keep up the humidity because I live in the desert and humidity is my biggest battle. I am starting to worry that it might not be a "clean" environment over time and also that mold could be a problem. Not to mention the feeder insects hide in the dirt. What would you all suggest as a better substrate?