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Old 04-13-2005, 06:47 PM   #1
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DIY CO2

So my understanding of this process is that the yeast consumes the sugar and CO2 is released as a byproduct. My question is this: How does changing the amount of yeast affect the rate of CO2 produced?

If thats a stupid question, sorry, but my thinking is that since the yeast multiplies and there is a maximum amount of sugar that can disolve in the water (excess sugar precipitates to the bottom) then wouldn't there be a maximum concentration of yeast in the water and therefore eventually, no matter how little yeast you put in, there is a maximum output of CO2. Obviously the amount of yeast added at the start of the process would determine the rate at the beggining, but I'm just wondering about a maximum output of CO2.

So my proposed answer to my question stated above is that given time, the output of CO2 is the same no matter the initial amount of yeast.

Of course my answer depends on the postulate that there is a limiting factor to the concentration of yeast in the sugar water. Is that true?
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Old 04-13-2005, 07:00 PM   #2
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Yeast will reproduce to a colony size able to consume the supplied sugar. Too much yeast at the beginning will cause a significant increase in initial CO2 production, and then it tapers off to almost nothing, very slowly finishing off the last bit of sugar.

If you start with less yeast, it takes longer for it to form a colony, and it'll actually form a smaller total colony since it's also converting sugar to CO2 and alcohol. It'll sense the alcohol increase, and stop reproducing, and simply consume sugar.

When you're making beer, you want enough yeast to quickly ferment the sugar, so that wild yeast/mold/bacteria doesn't infect it also, which gives off flavors or ruins the beer. When you're only concerned about stable CO2, a smaller volume of yeast is best.
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Old 04-13-2005, 08:14 PM   #3
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So the reason a large initial concentration of yeast will have the CO2 taper off to almost nothing is because there isn't initially any alcohol but there is plenty of yeast to consume the sugar, so a lot of alcohol is initially produced and then only a small amount of yeast will reproduce future generations.

Interesting. It makes sense that some waste product would come into play here (and thank goodness for all of us the "waste" can be used by humans )
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Old 04-14-2005, 03:58 AM   #4
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I'll be able to answer that question definitively this summer. In order to keep up my lab skills on my summer off of school, I plan on running an experiment to find out all about CO2 production
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Old 04-14-2005, 10:09 AM   #5
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You would not want to drink the leftover's from DIY CO2. table sugar doesn't ferment to a tastey drink. It'd taste more like lighter fluid, and would likely make you very sick to your stomach before providing any pleasant sensations. In fact, the way we sterilize DIY, versus the way homebrewers sterilize...you'd probably be sick a couple days.
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Old 04-14-2005, 01:21 PM   #6
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Speaking of sterilization, in a perfect world we would boil all the DIY components, or at least give them a dip in boiling water, every time you make a new mix, but I know I did not do that. I did in the beginning, as it was included in the instructions I received, but after a short time I got lazy and just rinsed everything out and made the new batch.

Experimenting with different quantities of the ingredients might shed some light on the process, if you chart the results. I'll personally wait and let Mike do the work for me....
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Old 04-14-2005, 03:25 PM   #7
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I can't imagine taking out my DIY CO2 2-liter bottle and guzzling that down 8O I just meant that it was good for everyone that yeast behaves the way it does.

I too would be interested in the results of CO2 experimenting... and, I too will not be doing the work.
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Old 04-15-2005, 04:15 AM   #8
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It does smell good though :P

Funny sort of OT story, I lost my last job for surfing the internet and giving someone "beer brewing instructions." I was checking this forum and giving instructions on DIY CO2. I guess those IT people weren't fish keepers.
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Old 04-15-2005, 06:14 PM   #9
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To increase the CO2 you can run a couple, or more soda bottle's in parallel. I use 2 bottles, the "formula" is supposed to last about 2 weeks. I change one each week, I figure this stabilizes CO2 a bit.

Most of my CO2 goes into my DIY ladder, and my DIY diffusion bell... but I also use some decoratively. I used to have a coulple bubble stones in decor for an interesting look, now I pump CO2 to get the look, and add a little more CO2 over all. Plus I have read standard air bubblers are not good for CO2 levels, but I sure like having some bubble coming up in a few spots.
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Old 04-18-2005, 05:22 PM   #10
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I too run 2 2-Liter bottles into my 55g. I'm still playing with the amounts of water, sugar and yeast to get the best results.

My first batch worked like a charm ... I actually had the bottles up on top of my PC light and it cranked out CO2 wonderfully. But my wife claims that my science experiment was an eyesore, so I have since moved the bottles down under in the tank cabinet ... but now it seems that I don't get near the consistency or amount of CO2. I'm thinking that my lights were keeping the bottles and mixtures warm ... so I'm thinking that temperature does affect the fermentation?

Can anyone confirm or shed some light on that? I'm hoping that since its getting warmer outside that my house will be warmer, thus increasing my CO2 ouput.
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