I'm by no means an expert here, in fact I'm probably more of a newbie.
Anyway..my 2 cents with experimenting as a casual novice...
A couple years ago I brought three big pots of Basjoos I had growing over the summer out on the patio in for the winter and had the same problem. I ended up purchasing a couple bottle of spray funguscide from Lowes and it seemed to do the trick very well. Just kept on top of them every couple of days until I could get them back outdoors in the spring.
My mistake was I placed the basjoos in the same room with my parrots and they like a little more humidity in the winter, probably didn't help the fungus situation that's for sure
Mouthwash is interesting....one thing I love about this site, you learn something new every time