Somehow I had the yeast scum crawl up the air hose. So I am redesigning mine. I am adding a second bottle. *lol* if I was thinking I would have had it like a water pipe (perk the incoming CO2
through some water).
One or two warnings I have heard. One is to make sure to keep up on it so it doesn't start producing alcohol (which will kill the fish). The second is to use a touch of something besides sugar (a spoon or two of OJ, tomato sauce, or whatever).