Gelatine CO2 Mix
Gelatine: 2 packets of Knox gelatine in 1 cup cold water, 1/2 cup sugar dissolved in 1 cup hot water, combine and mix, chill overnight.
Cube gelatine and add to 64 oz jug.
Add 1/2 teaspoon yeast to 1 cup warm water wait until it disperses, add 1/4 teaspoon sugar and wait a few more minutes to see some action, then add that and 2 teaspoons baking soda and another 3 cups warm water to the jug.
When the mix slows, I pour off half of the liquid, trying to keep the gel cubes in the bottle, then add more room temp tap water.
I've been using bread yeast, ale yeast, and champagne yeast. I think the bread yeast like the baking soda more than the beer and champagne yeasts do. I use a yeast nutrient with the beer and wine yeasts in addition to the baking soda, they did poorly with only baking soda. I will be looking at using less baking soda and more nutrient in the next few months, but the nutrient makes sticky foam when used in large amounts (1 teaspoon) but 1/4 teaspoon seems OK, some foam but not a foamover, at least when combined with baking soda and gelatine.
Bottles last about 3 to 4 weeks, so it takes a while to do many tests of different mixes.