Aspen always does that to me really fast if it stays wet and it only takes a few days. Cold only seems to slow it slightly. This is exactly the problem I was talking about long ago when I saw people were brumating their snakes on wet aspen. Then Stefan basically told me it doesn't seem to happen to everyone else. Well, what do you say now? This is the exact reason why I said wet aspen isn't a good idea. I just checked on my brumating snakes recently and around the dish where the aspen was wet, I had a fuzz garden growing and I just checked it 5 days ago and it was fine. I get that not all fungus growth is going to be harmful but if the harmless ones can grow, so can the harmful ones. . I don't think the above pic is "black mold". It's likely mildew but even that bugs the crap out of my respiratory system when it starts spewing spores in the air. ANY fugus spores have the potential to cause an immune response and irritate the respiratory system even if they aren't a particularly toxic species. I'd just rather not have any growing especially in a mostly enclosed environment like a plastic tub.