# Doubling DIY CO2 recipe



## jstehman (Dec 13, 2010)

If you double the recipe with a 2L, it will start out VERY strong, and then peter off about a week later as the yeast shuts down. Now if you were to use a 1 gallon Carlo Rossi wine jug...then yeah go for it. The Chianti jug lasted almost 4 weeks for me. The hardest part is getting the tubing to seal in the metal cap.

That original recipe works for me pretty well. In my 20 gal, I'm running that recipe diffused through a Hagen mini Elite, and the DC is green/light yellow for 2 weeks minimum.

You won't blow up the bottle. Ever drop a 2L soda bottle? Did it explode? You'll gas your fish before the bottle explodes.

I would just follow the recipe, or get yourself the 1 gallon glass jug and double it.


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## green_valley (Sep 14, 2011)

jstehman said:


> If you double the recipe with a 2L, it will start out VERY strong, and then peter off about a week later as the yeast shuts down. Now if you were to use a 1 gallon Carlo Rossi wine jug...then yeah go for it. The Chianti jug lasted almost 4 weeks for me. The hardest part is getting the tubing to seal in the metal cap.
> 
> That original recipe works for me pretty well. In my 20 gal, I'm running that recipe diffused through a Hagen mini Elite, and the DC is green/light yellow for 2 weeks minimum.
> 
> ...


Thank you for your response. That's what I meant, if you look at my "double" recipe, the bottle become 4L instead of 2. Thank you again for your suggestion.


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## jstehman (Dec 13, 2010)

Glad to share my experiences.


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## RoyalFizbin (Mar 7, 2006)

Many years ago, I atempted to mix up a batch in an eight liter detergent bottle. I scaled up the sugar but left the yeast the same as i would use for a standard 2L bottle. It lasted about the same with a higher volume of co2 produced. I can't remember exactly if it lasted slighty longer or shorter but it certainly wasn't worth doing again.


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## green_valley (Sep 14, 2011)

RoyalFizbin said:


> Many years ago, I atempted to mix up a batch in an eight liter detergent bottle. I scaled up the sugar but left the yeast the same as i would use for a standard 2L bottle. It lasted about the same with a higher volume of co2 produced. I can't remember exactly if it lasted slighty longer or shorter but it certainly wasn't worth doing again.


That's why I thought by doubling the yeast also might help.


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## nalu86 (Oct 19, 2010)

green_valley said:


> That's why I thought by doubling the yeast also might help.


It won't help, the production stops from the moment there is to much alcohol produced and the yeast starts dying.

So no matter how much yeast you throw in, it won't last longer (yeast reproduces super fast)


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## green_valley (Sep 14, 2011)

nalu86 said:


> It won't help, the production stops from the moment there is to much alcohol produced and the yeast starts dying.
> 
> So no matter how much yeast you throw in, it won't last longer (yeast reproduces super fast)


hmmmmmmmmmm......so you're saying, regardless how much and how big the recipe is, it will only last for 2 weeks?????


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## jkan0228 (Feb 6, 2011)

If you double everything, then you'll just get more co2 but in the same period of time. This is what I think: if you want it to last longer, maybe double the volume of water and more sugar? But you don't wanna double your yeast.


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## Wasserpest (Jun 12, 2003)

Yep, if you double the recipe/volume, you will get twice the CO2 output, but no extended lifespan.

I have tested the gravity of some DIY setups over time, and was actually surprised to find how little sugar had been turned into alcohol after it pretty much stopped bubbling. Perhaps the missing yeast nutrients are the culprit.

Test this - instead of using the old "2 cups of sugar" try a single cup and see if it makes any difference either way. Some folks use the messy "Jello" method which extends the activity somewhat. Not sure if the mess is worth it, mixing up some sugar and water is very simple.

I had bubbles going for over a month in a colder environment... temperature affects the reaction (fermentation) a lot, with cooler temps = less output = longer duration.

Just some things to ponder...


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## Patty LongD (Jun 9, 2013)

Here's my contribution to this fascinating thread: use way less yeast but the same two cups of dissolved sugar. Like 1/4 to 1/2 a teaspoon of yeast. Mine lasts for two months solid. 1 Gallon plastic Crystal Geyser jug, simple $7 diffuser, 15 gallon tank, room temp. Two months and going strong, I just changed it for fun. Literally. Enjoy.


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## Texex (Aug 15, 2003)

Years ago at the AGA Convention in Dallas, Tarah Nyberg presented a talk about how to generate CO2 with optimized conditions. She was a graduate student at UT Southwestern Medical School in Dallas getting her PhD in yeast genetics, so I figured she knew what she was talking about. Anyway, here are some of the points that she emphasized in her talk and that were put into practice in my tanks.

1) Yeast do not tolerate ethanol and sugar above 10% total volume. So, if you use 2 cups of sugar (500ml) per 2 liters of water, your sugar concentration is 25%. That's 15% of the sugar wasted, since yeast quit fermenting after the ethanol reaches 10%. So, I used to use 1 cup of sugar/2 liters of water which will be below the ethanol tolerance of the yeast.

2) Yeast need additional nutrients to stay healthy. When the yeast is rehydrated, they have a store of proteins that is used in fermentation of sugar to CO2. Over time, that store is used up and the yeast will need nutrients to supplement their "diet" in order to synthesize the proteins needed to continue fermentation. Tarah recommended adding 1-2 teaspoon of a protein mix (just make sure it has proteins and vitamins and minerals), or if you can find some yeast extract, that's even better.

3) (Optional) Yeast also like ammonia, so add some ammonium sulfate (1 teaspoon) or 1 tablespoon molasses as an ammonium source. I skipped this step and my fermentation was fine.

4) Buffer the yeast with a bit of baking soda. The pH of the solution will drop during fermentation, so adding a buffer will keep the pH in the healthy range for the yeast. I used to buffer between 7-8.

5) Use champagne or wine yeast, both of which are more tolerant of higher ethanol concentrations. I had great luck with a strain that was not only more ethanol tolerant, but also temperature tolerant. Yeast like to be warm, but the champagne yeast I used even worked well at low temps (especially important in the winter).

6) Finally, decant to liquid part and retain the yeast sludge at the bottom of the bottle. The healthy, growing, fermenting yeast are in that layer. The stuff that's floating (flocculant yeast) is dead and should be poured out when you make a new mix.

I used a 3 liter wine bottle for my container and make 2.5 liters of the mix each time. I was able to generate a slow steady release of CO2 for 3-5 weeks depending on how long I had the yeast. I reused the same yeast for over 2 years before I finally converted full time to a Co2 system. Hope that helps some.

Texex

Forgot to add, I only used 1/8 a teaspoon to start up the yeast. It might take a bit of time to get going, but the density of the yeast will increase gradually and utilize the sugar in a more controlled fashion. If you use too much yeast, it starts up too fast and you end up getting a CO2 spike followed by a fairly rapid decrease in CO2 generation. By using less yeast, the yeast will multiply to equilibrium where the yeast multiplying equals the yeast dying. If you use too much, the yeast will burn through the sugar to the ethanol limit and then they will start dying off until levels can be maintained in equilibrium. Hope that made sense....


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## jkpedrita (Jun 5, 2013)

Texex said:


> 2) Yeast need additional nutrients to stay healthy. When the yeast is rehydrated, they have a store of proteins that is used in fermentation of sugar to CO2. Over time, that store is used up and the yeast will need nutrients to supplement their "diet" in order to synthesize the proteins needed to continue fermentation. Tarah recommended adding 1-2 teaspoon of a protein mix (just make sure it has proteins and vitamins and minerals), or if you can find some yeast extract, that's even better.


I feel like this is probably a stupid question but by protein mix do you mean like the whey protein exercise stuff?


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