Homemade Co2

[Faffer]

When you think it through, you will realize that yeast is a living organism that is using the sugar to grow and increase its numbers. That means that your mix contains a good source of starter material for the next CO2 bottle. You can seed the second batch by simply using some of the first batch as a starter. Every few batches, you might want to use fresh yeast but you can produce several bottles from a single dose of yeast.

Does that mean you can simply just add sugar every week or will the alcohol kill off the yeast, so you need to dilute it with new water?

 

[OldMan47]

The thing that stops a DIY system is the alcohol concentration, not running out of sugar. As long as you start a new batch before the old one is killed off by the alcohol, you can keep using the same yeast culture. Eventually it will be contaminated in one fashion or another and you will need to start a batch from scratch.

 

[chrisbassist]

How about giving it to your mother in law to drink? She'll drink anything if it's topped up with lemonade...

Seriously I Am paying attention here... Gotta try and make sure my system gets run right.

 

[Faffer]

What is the advantage of using the existing yeast culture over starting from scratch, other than saving a few pence on yeast? Will the existing yeast start producing CO2 at full speed straight away? I've only recently set up my CO2 kit, but I notice it takes a good while (eg. overnight) with a new mix before the bubbles start coming out at a decent rate.

 

[RadaR]

As far as I can see there isn't an advantage. The reason why the CO2 production eventually dies down is because the ethanol being produced is killing the yeast. So using an already existing yeast culture that as experienced levels on ethanol can't be good in my opinion. A fresh 1/4tsp of yeast would be better.

 

[OldMan47]

Actually, Radar, the batch set up using a previous batch of yeast and sugar does not see the high alcohol levels of the dying culture that you have. The new culture has no such problem. That means that it does not become reduced by seeing high alcohol levels. The end result, as long as the culture has not become contaminated by other yeasts and bacteria, is that the new culture will take off as if the culture resulted from a brand new culture. Respect for just such possible contaminations is the very reason that every few cultures should be started with new yeast rather than using the surviving yeast from a previous batch.