I have a small covered run, dirt floor. I live in Washington so it's wet. Not muddy, just damp. I wrapped in plastic to try to keep dry and warm, the ground gets slightly wet when it rains bad, no standing water but damp. I'm starting to notice white mold growing on the wet dirt. I've been rakeing it out everyday but I'm wondering how to prevent.... My thought is to add sand. Do you think that the mold will continue to grow under the sand? Any advice or thoughts appreciated!