Improvements on DIY CO2, or How I got 20 ppm in a 100 gallon on yeast and sugar - The Planted Tank Forum
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post #1 of 11 (permalink) Old 03-17-2010, 02:26 PM Thread Starter
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Improvements on DIY CO2, or How I got 20 ppm in a 100 gallon on yeast and sugar

Greetings, everybody.
This is my first post here, and I make it 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.

This is a continuing voyage. Next stop: Lighting upgrade.
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post #2 of 11 (permalink) Old 03-17-2010, 05:20 PM
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Thanks for the info. I have been using brewers yeast for a while since it seemed the logical choice but I never though of adding fish food. COnversely I see similar results in my 80 gallon simply by using 2 2 litre pop bottles. I stagger them so I basically have to change one or the other every two weeks. GOnna try fish food next time. I also add baking soda as a stabalizer for the solution
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post #3 of 11 (permalink) Old 03-17-2010, 05:27 PM
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holy cow. Nice info. How long does your mixtures last?

I went away from DIY co2. I couldnt keep up with swapping out the mixture and not getting ph swings. Bent over and took it lol
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post #4 of 11 (permalink) Old 03-17-2010, 11:59 PM Thread Starter
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The mixture should last about 2 weeks. I'm closing in on 2 weeks on my first batch and it's still going. In my winemaking experience, grape juice takes about 2 weeks to finish primary fermentation, the stage when it is rapidly producing CO2.

@WilliamS: You mentioned brewer's yeast, which by strict 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 :p

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.
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post #5 of 11 (permalink) Old 03-18-2010, 09:36 PM
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I'm using 5 pounds in a 5 gallon jug. I used only part of a champagne yeast packet and added a bunch of baking soda and yeast nutrients. A month later I'm still getting about the same output. If I let air in the yeast reproduce and the CO2 rate shoots up, so I try to avoid mucking with it as much as possible. A pound of sugar generates 6 gallons of CO2 gas at 72F (Typical house temperature ranges don't affect the volume much). At 1 BPS with a 1/4" bubble, I'm looking at 1.5 years of CO2 production if it remains at a constant level for 5 pounds of sugar. I'm able to maintain green on my drop checker by feeding the CO2 into my powerhead venturi, which isn't all that effective. Combined with two HOBs degassing the surface...
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post #6 of 11 (permalink) Old 03-19-2010, 04:42 AM
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I add a half tsp of Marmite to my DIY jello mixture and I get over a month out of a 2 liter bottle. I use two bottles on my 29g and get between 20 and 30 ppm consistantly. (two cups of sugar and 1 tsp of yeast) It's fed into a HOB filter though there's not much surface agitation.
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post #7 of 11 (permalink) Old 03-19-2010, 07:59 AM Thread Starter
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Looks like your strategy is a bit different:Higher volume, lower temperature. I might move that way once things get stabilized. However I think 1 pound sugar yields much more CO2 than 6 gallons. If 80% of your sugar gets burned, then 40% will be CO2, let's say 180g, which is roughly 40% of a pound. 1 mole of CO2 is 44 g, so you're looking at at least 4 moles CO2 per pound sugar. 1 mole of gas,IIRC, is 22.4 liters at standard temperature and pressure, so about 90 liters, so 1 pound of sugar should produce 24 gallons CO2 by conservative estimates. Correct me if I'm wrong.

And if anyone wants to try fish food, start it in a test environment before hooking it up to your tank. Some fish food might contain preservatives and fungicides, so your mileage will definitely vary. I tried mixing some in a cup with some yeast and sugar last night, and by this afternoon no action. I think the yeast were actually killed. Oh well, can't expect everything to be a success. I'll stick to yeast and lemon juice:

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.
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post #8 of 11 (permalink) Old 03-21-2010, 02:55 AM Thread Starter
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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.
(do a google search, I'm not privileged to post links)
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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post #9 of 11 (permalink) Old 03-21-2010, 03:23 AM
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im a brewer too and im wanting to know how you monitor your co2 intake throught primary fermentation as opposed to secondary where its much slower? i felt like the co2 worked thruogh primary but once a 5% alcohol solution was produced the fumes off the alcohol had adverse affects. aka beer was good wine was not after about 2 weeks. are you bubble counting and monitering ph values and disconnecting during the daytime? and how do you regulate your co2 production? mine blasted for a week then slowed.
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post #10 of 11 (permalink) Old 03-21-2010, 12:11 PM Thread Starter
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(do a google search on "wine primary fermentation percentage". it's result number 2

"The Primary Fermentation will typically last for the first four
to seven days. On average, 70 percent of the fermentation
activity will occur during these first few days. And in most
cases, you will notice considerable foaming during this time of
rapid fermentation."

I can theorize on what is happening. Because I'm using wine yeast in an imperfect environment, that is, home-made yeast nutrient and sugar water as opposed to the grape juice they've been bred and selected for, the primary fermentation slows down. I did mention before that I tasted it and it seemed like it was about 70% done. Should've gotten a specific gravity.

Before adding CO2, my pH stood at 7.2, and for the next week after hovered around 6.6, 6.8.
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 several hours ago and it's still getting up to speed. Heat's on, maybe I should take it off to extend early primary.
I'm confused why you should ask if I disconnect CO2 during the daytime. If anything, I should disconnect it at night, but I don't. Contrary to popular myth, CO2 at night won't interfere with the plants' "dark cycle". It may be possible to blow out your pH and kill your fish and more delicate plants, but my pH measurements in the morning stand around 6.5 when I have around 80 bpm.
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. But 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.
It ain't perfect, but I'm hoping some clever non-conformists can help me make something of it.
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post #11 of 11 (permalink) Old 03-21-2010, 06:33 PM
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youre right with the day/night cycle, my bad. this sounds like its working good for you. i have some frementation suggestions for you. after primary you turn the heat up to get another boost. if you add a little more sugar you can draw this process out even longer. and if you get high gravity yeast your solution can produce up to 22% alcohol so youll be changing solutions even less. if you only add a tiny amount of yeast your primary will start slower and not pound out the co2 so fast while the yeast produces new cells. holding off on yeast nutrient until the end will also extend the life of the solution. i too used to put co2 to my tank until i got too greedy and had some mead blow off into the tank crashing it so remember to always leave plenty of head space in your bottle.
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co2, diy, yeast

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