# Improvements on DIY CO2, or How I got 20 ppm in a 100 gallon on yeast and sugar



## huaidan (Mar 6, 2010)

I'm making this post because I feel compelled to share with you my good fortune in re-engineering the diy co2 yeast and sugar method. Maybe re-engineer is too strong a word, however I did modify the method to some measure of success.
Let's get down to brass tacks then, shall we?

First, the method is scalable. This means if you get a certain rate of co2 production out of 2 liters, then, everything else being equal, you will get twice as much out of 4 liters. So I modified a 5 liter plastic jug, which didn't have a secure cap, to fit a 2 liter bottle cap, to which I air-tightly fixed aquarium tubing. Do this any way you deem feasible, but just remember production can be increased to any practical size the situation demands or allows. In my situation, for 100 gallons, 5 liters was sufficient.

Now, I'm an amateur brewer and winemaker, so I know a thing or two about yeast. First thing you need to know is that there are different kinds of yeast. Winemaking yeast, which you'll either need to order online or visit a brewer's shop, is essential here because it produces CO2 more vigorously, let me rephrase, MUCH more vigorously, than breadmaking yeast. It also finishes more cleanly, so when it slows down you know it's almost dead, it won't weaken slowly over a week like bread yeast will in the alcohol it produces. Not least important is winemaking yeast's ability to live longer in higher alcohol concentrations. This is an overwhelming advantage. It means you burn almost all your sugar, so your CO2 consumption can be measured in sugar consumption! Remember, 180 grams sugar can theoretically produces 88 grams CO2. I'd safely bet you can get nearly 80. A pound of sugar can yield 200 grams of CO2 over three weeks. I'm using 2.5 pounds. You'll need a teaspoon of yeast, it multiplies quickly.
Next thing about yeast: They can't live on sugar alone. Not well enough to produce CO2 with maximum efficiency, anyway. You'll need yeast nutrient. I've used my own concoction, in which I heat-killed bread yeast in pure lemon juice, (more like pasteurizing, less like cooking) for about 15 minutes, with resulted in a creamy slurry. I froze this into ice cubes to complete the lysing process. 2 ice cubes per 5 liter, yum. Next time I'm going to try fish food, seriously. All you need is protein, vitamin c, and potassium and phosphates. Yeast need it to grow and reproduce and metabolize strongly. Fish food might be the ticket, considering I'm not going to drink the stuff. 2 tablespoons ought to do it, mixed thoroughly in solution..
2.5 pounds of sugar, already mentioned that. Fill to below the neck with lukewarm water, give some room for foaming.
Put your rig into a stable bowl or basin of water, with water up to 2 or 3 inches up the side of the jug. put a small 50 watt aquarium heater into the water where you can fit it. If you can't fit it, you need a bigger bowl or basin. Keep it around 30 degrees centigrade, or about 85 F. Wine yeast takes some time to get started , so you may have to wait 12 hours or longer to see any action. You can add more wine yeast and speed things up some, but only if you're desperate. It seems a waste otherwise. During this time, you can check your setup for air-tightness, because it won't be producing much CO2 at this time. You know when it's started., and you'll see crazy bubble counts starting soon after, during the next day.
I feed mine into an auxilliary output on a filter powerhead, which does a great job in atomizing the CO2. I get a healthy spritz every 1 to 3 seconds, saturating the tank in a CO2 mist. I can expect this rate for 15 to 20 days, after which I'll need to change my solution. In all honesty, I haven't checked my KH, but my pH was 7.2 before dosing and now it's 6.5. That's with an out-gassing overhead biofilter. If that's not 20 ppm, it's in the neighborhood. Bubble count is off the charts, at least 80 bpm. They come out in clusters so it's difficult to be completely accurate.

You may want to turn off the heater when the lights are off to prevent overgassing. If you wish to slow down or cut off the CO2 supply, do not do it with a valve, as the pressure could cause a rupture or an explosion, hardly dangerous but messy and counterproductive in any case.
Brewer's yeast,by its strictest definition, is beer making yeast. I strongly suggest wine making yeast. Yes, it's different. There's even different strains of winemaking yeast, for your different kinds of wine, believe it or not. If you have a choice, get whatever has the highest alcohol tolerance, such as a sherry or cabernet variety. No, I'm not pulling your leg. The longer your yeast can live in a high alcohol concentration (more than 15% is the target), the more of your sugar will be converted to CO2. Just don't try drinking it if you use fish food as yeast nutrient 

I haven't tried fish food as yeast nutrient yet, but I'll give it a go on my next batch. A complicating factor could be the presence of a preservative or a fungicidal agent in the fish food which would kill the yeast. Trial and error will determine.

This is a continuing voyage. Next stop: Lighting upgrade.


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## doubleott05 (Jul 20, 2005)

holy smokes very informative. good job iwth your home work... which brings me to my next point children. 

"why do your homework when you can copy somebody else who has done it for you"?
Doubleott05

thanks for sharing


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## Diana K (Dec 20, 2007)

Great details! If fish food has antifungus that kills the yeast would something else work?

Agar or gelatin as a source of protein?
A vitamin C tablet? How many miligrams? Lets see... 2 ice cube trays of lemon juice (but some of this was yeast) = about 1 lemon... 
Nutrients from Wikipedia:

* Vitamin C - 45 mg
* Calcium - 22 mg
* Potassium - 116 mg
* Carbohydrates - 7.8 g
* Protein - 0.9 g
* Fat - 0.25 g
* Calories - 100

Aquarium fertilizers such as KH2PO4 for K and P? How much of each? Is this one a good balance by itself?


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## Big_Fish (Mar 10, 2010)

Nicely written... I make BEER.... but you're absolutely right about WINE yeast specifically... 
http://www.midwestsupplies.com/red-star-wine-yeasts-5-grams-premier-cuvee.html 
this one in particular stays active to 18% alcohol! Between the yeast, and your explanation (different post) that orange soda does provide SOME nutrients for the yeast... I now have a plan to get my DIY rig running better than it is now. (and I'm happy as could be with how well it's working now)


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## huaidan (Mar 6, 2010)

@Diana:

I experimented with yeast nutrient when I made a few batches of Mead, honey wine. Living where I do, it is difficult to find proper commercial yeast nutrient, so I did a little research and formulated my own. My recipe was an overwhelming success for both the mead project and the CO2 injection.
Most of the nutrients the yeast need are contained in yeast cells, but the nutrients are encased in tough yeast cells walls. Heat, acid, and freezing will lyse (rupture) the cell walls, making the nutrients available in solution. Lemon juice has the acid, and it also contains plenty of vitamin c, which is pretty much universally required by every living thing.
It's nutrient for microorganisms, so no need to be too specific in the measurements. I took about three tablespoons cheap bread yeast (of course wine yeast is more expensive, you probably could have guessed that, don't use it for your nutrient), and completely juiced a large lemon (maybe 2 small ones will do) and mixed. In my mix I also added a trace of water to smooth out the mixture to make a creamy slurry, like melted ice cream in consistency.. I used a bowl-inside-a-bowl of hot water to gradually heat the yeast mixture to near boiling for about 15 minutes. Then I froze into ice cubes. Make sure they're frozen solid (24 hours) before using. This recipe should make about 1 standard ice cube tray full of yeast nutrient.



Probably most confusing to the readers here is that I'm using 2 kinds of yeast. The winemaking yeast will be alive, producing boatloads of CO2. Bread yeast is killed and ruptured in lemon juice, so the wine yeast can cannibalize them, allowing the wine yeast to be fruitful and multiply and do their job.

@BigFish
18%? Wow, hope I can get some of that. Why did that just make me want to have a drink?


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## wet (Nov 24, 2008)

Well done, huaidan. Only a suggestion: adding another post as numbered steps may help many people and popularize your method. I was surprised to read some folks avoid pressurized and stick to yeast-based CO2 because they think pressurized is too complicated. I think your ideas and experience will be very helpful to those folks when paired with numbered steps.

Only an idea. Good work regardless, and the ~90% possible output by grams sugar is also something neat I've never seen before <3


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## huaidan (Mar 6, 2010)

@Wet

I'll get a step-by-step together after I have a more refined version of this procedure. I hope, ideally, others can give this a go and suggest their modifications.

Right now, I've just uncovered a major drawback. The solution needs to be replaced every two weeks in order to maintain high CO2 output. Yesterday, at two weeks, I noticed dropping CO2 levels, so I did a bubble count, which had fallen to 7 or 8 bpm. Primary fermentation has ended, and the subsequent bubble count was insufficient. 
I tasted the solution next, for residual sugar. It was a bit sweet, so I'm guessing I'm getting around 70% efficiency in sugar consumption. Now, this alone is not a big problem. I could have taken a specific gravity of the waste solution and used this value to get a precise measure of the residual sugar concentration, but I was a complete idiot and dumped the solution before I thought of that. If I had known the exact concentration, I could have calculated from the original concentration (2.5 pounds in 5 liters) the amount of sugar consumed, then multiply by 88/180 to get the mass of CO2 produced.

So, conservation of matter cannot be violated, and high output of CO2 means quick depletion of sugar. When this batch finishes out, I'll be sure to record the sugar concentration. This site has a conversion chart of SG to sugar in solution, very convenient me because it includes a column for 4.5 liters.
http://www.home-winemaking.com/winemaking-2b.html
Two things to consider if taking a SG reading:
1. The sample should be heat killed or killed by some other method. CO2 coming out of solution will affect the SG reading, so this must be stopped before measuring. Heat killing the sample must include measures to prevent evaporation, as this will also affect the SG reading.
2. SG readings taken precisely will still be artificially low due to alcohol in solution, as alcohol has an SG of 0.79. I'd have to do some research to find out exactly how much, but considering dry red wine has a SG of 0.99, it shouldn't be off by much.


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## wet (Nov 24, 2008)

When I did DIY CO2, I was a big proponent for short lasting mixes using two staggered bottles, each started a week apart, to raise the minimum level of CO2 in the tank. Very effective. Have you thought about doing the same with this much more efficient mix? If you can figure out what the nominal output is after x amount of time, maybe staggering them two weeks or more apart will be just as effective while giving you a pretty good ball park of CO2 input into the tank?


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## ghengis (Jun 11, 2008)

At last, someone with a useful viewpoint on a well flogged topic. I almost didn't open this thread, as I thought "just another noob that wants to re-invent the wheel"...I am pleasantly surprised! 

Nice info, huaiden, thanks for posting


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## huaidan (Mar 6, 2010)

I like Wet's idea. Next week I'm going to rig a splice into my CO2 line and start a staggered batch, then apply heater to old batch.
I didn't add the heater until day 9 or 10, which might have given an extra kick during later primary.
Immediately before I added the heater, I took my first real bubble count, which , although a bit disappointing at 30, was not insignificant. After adding the heat bpm increased to nearly 80, it was difficult to determine exactly. pH next morning was 6.5. This went on for another 5 days, until the spritzes coming from the powerhead started looking really weak.
I just changed solution yesterday. Heat's off, seeing as the initial primary fermentation really doesn't need any help.
Regarding regulation, it ain't there, not in the gas flow itself anyway. That would be impossible without some kind of pump-gas compressor reservoir, which would really defeat the purpose of DYI. While trying to boost my lagging CO2, I added a heater to a bowl of water and kept the jug in the bowl of water, as described above. In doing this, I may have discovered a way to regulate production by temperature. Where I'm at, room temperatures can get down to 15 centigrade this time of year, which keeps even violent primary fermentation mellowed down a little. This will change later in the year so I won't always have this option, but even a change from 25 c to 30 c makes a huge difference in gas production. Right now I'm thinking about applying heat to the last week of the older batch.

And this just occurred to me: It is quite likely with 2x5 liters going that I will be producing a surplus of CO2, in which I would risk overgassing the tank and sagging my pH. I could scale back production with smaller bottles, but maintaining a good CO2 balance could be tricky game of trial and error in this case, involving supply-side quantitative analysis.
Alternatively, I could keep the proposed surplus production, and use a three-way valve between the jugs and the powerhead to blow off excess CO2. By doing this, I would be disposing of an unknown quantity of CO2, and lose the ability to calculate the amount of CO2 injected into my tank from the amount of sugar consumed, seeing as this would amount to an unknown quantity less than 100% of the total CO2 produced. This would entail the launch of another project: the drop checker. I should have one anyway, come to think of it. Come to think of it again, determining the amount of sugar consumed only reveals the amount of CO2 produced, which conceivably could be useful information for some purposes. However, it's a pretty flimsy determiner of the amount of CO2 in the water. It's a theoretical value that can be used to determine efficiency.

900 g sugar x approx. 70% sugar consumption x 88g CO2/180g C6H12O6 / 2 weeks = 150 g CO2 / week. = 20 g CO2 / day on average.

Does anybody know if this is a recommended rate of CO2 injection for a 100 gal tank?

Coupling the staggered CO2 "plants" with temperature regulation might give me a more robust, evenly regulated CO2 flow. Although high-maintenance, with the weekly changes, it seems to be approaching true functionality for a large tank system.

Look what I just found on taobao. $4 USD. I can have it in two days.

http://item.taobao.com/auction/item_detail-0db1-816ae92ca4796319ed96831c779843ff.jhtml?cm_cat=0

Think I'll skip DIY on that.


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