I used to make a lot of wine, and wine fermentations go on for many months. I
have had slow fermentation for over a year. COOL THE BLASTED FERMENTER OFF!!
Wines are fermented at LOW temperatures, which controls the rate of
fermentation. Wine ferments are also ACID, very acid. Usually tartaric or
malic or citric acids, also a lot of other organic acids.
Seems to me a person could set up a 5-gallon carboy in a cold basement and
just pipe the CO2 upstairs through tubing. Don't use so much yeast to start!
Actually, you could just make wine, and pipe the CO2 to your tanks. No, I am
NOT joking! You can also store the CO2 until needed, either in a big truck
tire inner tube, a tractor inner tube, or the "upside down barrel floating in
a slightly BIGGER right side up barrel" contraption we used to use to store
methane for cooking.
Just a thought.