I do a little homebrewing/distilling. Whenever you make your wash/mash you basically mix 1 gallon of water low ph around 4. 3-4 cups of sugar, 2 tablepoons of bread yeast, and about a cup of some type of cereal with no preserv. You can use Gerber Baby cereal doesn't matter which one. Mix all this in 70-90 degree water. It can't be over 90 degree F. If it is it will kill the yeast. Add yeast last and let it set for 30 minutes and stir vigorously for a couple of minutes.
This should be done in a bucket with sealable lid with an air lock. The air lock can be purchased at a beer making store but you could just lay a rag over a small hole cut in the lid. The mixture will generate CO2 for 7-14 days. When it stops bubbling you have beer or mash ready to distill and your plants have CO2 in the meantime.