What is your favorite DIY CO2 recipe?

[Squawkbert]

For regular baking yeast, use 3 parts water, 1 part sugar, small amount of yeast. It is good to dissolve the sugar first.

Temp - don't sweat it, your yeast will activate at room temp, it's easy to kill if you go too hot.

Amount of yeast - it will multiply at a malthusian rate until it pretty well covers the surface of your container (I think if you want more CO2 over fewer days, use a shorter, wider container - not yet tested), so this doesn't matter a lot though using more at the start may kick things off and get you to "steady state" production rates faster.

Amount of sugar - using a 3:1 water:sugar (volume, assuming granulated sugar) ratio will result in the sugar being used up right about the same time as the ethanol concentration is killing off the majority of your yeast cells. Any more, you're wasting sugar. Any less, you're wasting time (having to redo it more frequently). I've done the experiments & the math behind these assertions.

Baking soda - No. Sodium ions are harder on the yeast than the pH change due to fermentation is (so I've read from reputable sources).

 

[magakitty]

I thought baking soda stabilized the mix

 

[tackful]

Since adding baking soda to the mix I now get about 2 1/2 weeks out of a 2 liter bottle, as opposed to just 1 week without it. I use baking yeast, and I read that the baking soda absorbs the alcohol which eventually kills off the mixture. Also heard that champagne yeast is best at tolerating alcohol; "Geofied"s 4-6 weeks with a 1 liter bottle seems to confirm this. The rest of my mixture is: 2 cups sugar, 3/4 teaspoon yeast, warm (not hot!) water up to the curve of the bottle. Tackful

 

[Squawkbert]

double your sugar, leave out the baking soda - you'll get nearly a month from it

baking soda does nothing to the ethanol, it will buffer the pH but the pH swing is much less harmful to the yeast than the sodium ions are

true abt Champagne yeast - but it is shipped wet, can die in transit and is expensive, but it is abottom fermenter meaning that you need not add more if you pour carefully and don't go too long (starving it, poisoning it) between sugar/water changes.

 

[snickle]

This is what I use in my hagen:

Hagen CO2 Mixture

Sugar to first line (1/2 cup)
1 teaspoon protein powder
1/2 teaspoon ammonium sulfate
1/2 Teaspoon Molasses
1/2 teaspoon Baking Soda
1/8 teaspoon champagne yeast
Warm Tap water to 2nd line (2 cups)