Does anybody know what is effective on the stuff that blackens the medium in CP pots and looks like mildew? Does anyone know exactly what that is? Some came in with a plant I got from someone, and now I have it on the medium in several pots that are out in the open. I've never had this problem before, and I need some advice. The odd thing is that there doesn't seem to be a problem in any of the tanks, which are a lot more humid. I need something that would be safe for nepenthes and drosera.