Because, as far as I understand (my knowledge, admittedly, is limited), airlocks are needed during fermentation for the sole purpose of letting excess gas (CO2) escape, would it be possible to use balloons instead? A balloon would serve the same purpose - it would allow fermentation to occur while letting CO2 leave the beverage, albeit not the fermentation tank. Or is an exchange of gases necessary for fermentation? I ask because no local dealers sell airlocks, so I would have to order online. I decided to check if I could use a balloon over the top of my fermentation tank instead before ordering an airlock. Thank you.