# sugar to yeast ratio?



## clincoln9 (Mar 20, 2013)

I've been playing with DIY co2 for a while and can't seem to figure out the perfect ratio of sugar to yeast. what ratio do you use? I read somewhere that you can alter the ratio so that the yeast will either produce co2 rapidly or slowly for greater longevity. Is this true and what would be the ratio for either case?


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## DeDeuce (May 18, 2007)

I always used 1 cup of sugar, 1/2 tsp yeast, and 1.5 liters of water. It would last for around 2 weeks. From what I understand if you use champagne or brewers yeast it will last substantially longer. I think the premise is that alcohol is a by-product of the fermentation process. As the alcohol level increases your yeasties start to die off. Champagne or brewers yeast are more tolerant to higher alcohol levels so the fermentation process continues longer.


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## herns (May 6, 2008)

2 cups of sugar with 1/4 tsp yeast mixed in a big size soda bottle.
i tried brown sugar and really last longer.


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## Solcielo lawrencia (Dec 30, 2013)

It's NOT about sugar to yeast ratio; that's irrelevant. Ideally, you'd have just enough sugar before the yeast poison themselves to death. What's more important is the kind of yeast you use. It should be low-temperature tolerant; otherwise, CO2 production will drop whenever the room temperature drops. I've been able to run yeast CO2 generators for more than 2 months using larger volumes of water which dilute the alcohol.


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## DarkCobra (Jun 22, 2004)

It's not really a ratio.

The amount of yeast controls the production rate. It will continue producing until sugar starts to run out, or alcohol builds up enough to kill the yeast; whichever comes first.

Here's my base recipe:

2 liter bottle
1.5 cup sugar
1 tsp yeast

And I know from experience this will produce CO2 at a fairly stable rate for about two weeks. At which point the alcohol will start killing the yeast, leaving a small amount of sugar behind and wasted; though not much.

If I find (also through experience) I need half as much CO2 as the base recipe produces, I use 1/2 tsp yeast. This also about doubles the time, to about 3.5 weeks. It's not exactly double, as there's a practical maximum limit to reliable production time for many reasons.

If I find I need double that amount of CO2, I use 2 tsp yeast. This also halves the time, to one week. But let's say I want double the amount _and_ two weeks.

I cannot simply increase the sugar past 1.5 cups. Any more will be wasted, since before it is used, the alcohol will start killing the yeast. So I use a bigger bottle, with twice as much water; since this dilutes the alcohol, then I can double the sugar.

And by using these rules I can produce a recipe with pretty much any characteristics I want.

Make sense?


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## darthmilmo (Feb 19, 2013)

I actually ferment my own wine using a recipe from this very forum. The trick is to have multiple smaller bottles and to change them every 5 days or so. Check this link out. http://www.plantedtank.net/forums/showthread.php?t=290122


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## clincoln9 (Mar 20, 2013)

DarkCobra said:


> It's not really a ratio.
> 
> The amount of yeast controls the production rate. It will continue producing until sugar starts to run out, or alcohol builds up enough to kill the yeast; whichever comes first.
> 
> ...


Thank you so much this is great! I had never even thought of the idea that the alcohol produced kills the yeast if not diluted sufficiently. I guess I just assumed they used all the sugar or just kinda died off...always glad to learn! I'll give this a shot and see if I can get my hands on some brewers yeast and give that a shot as well. 




darthmilmo said:


> I actually ferment my own wine using a recipe from this very forum. The trick is to have multiple smaller bottles and to change them every 5 days or so. Check this link out. http://www.plantedtank.net/forums/showthread.php?t=290122


This is a brilliant idea....you may have just introduced me to another hobby


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## darthmilmo (Feb 19, 2013)

You're welcome


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## jkpedrita (Jun 5, 2013)

Adding .5-1tsp of baking soda will also serve as a buffer and allow the yeast to run for longer. Champagne yeast works beautifully.


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