Hi. I have been using pressurized CO2 initially, but I've had enough of them. I had to change the container yesterday, and note that I had it on very low pressure so that her little would come out, but I discovered this morning that it was already all used up! And since these are expensive, I figured making my own CO2 is much less expensive and easier to maintain. Anyhow, since I live in Japan, and champagne yeast is imported (which means it is pretty expensive), I was wondering if there are good alternatives to this yeast. Thank you for your help!