Thank you. The sides are mesh, so ventilation should not be a problem. There is a large drainage layer. That leaves springtails. I have seeded a large amount already. I actually have a whole bunch in the coal in a container. Will add them right away.More springtails, they feed on mold/mildew/fungus. You may have a ventilation issue as well. Make sure you have good airflow, this will help dry out the enclosure faster, knocking down your mold problem. I guess a third issue could also be your drainage. Make sure there isn’t standing water in you bottom drainage layer. Hope that helps.