# How much co2 per 2 liter (sugar, yeast)



## CaptainW (Apr 15, 2010)

I have been researching on how to build a home made co2 generator with the sugar yeast combo, few questions. I am in a 4/4/7 tent.

1) How much co2 is dispersed into the air per 2 liter bottle?

2) How many bottles is safe to run? 1500 is max ppm without a reg or meter the amount of bottles to hit 1000 would be better than nothing.

3) Will it do anything for my buds, I want some juicy nug's this time around. I am growing two Sativa dominant strains would like to see some huge ones .

I know its a constant flow of co2 with the sugar yeast trick, so its hard to answer some of those questions. I am just looking for a generalized amount of 2 liters i should be using.


+rep to anyone who hooks it up with some knowledge!


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## homebrewer (Apr 15, 2010)

There is a totally worthless recipe found on page one here: https://www.rollitup.org/general-marijuana-growing/258474-homemade-co2-guide.html

As a brewer, I put together the details behind his recipe (because no one else knew them) and why it won't work. I also added a more realistic recipe with a larger batch size to correct the original recipe. 



> The concoction on page one yields a specific gravity of around 1.081. For you beer and wine drinkers, that's enough sugar to produce 10% alcohol assuming complete attenuation. Maltose isn't 100% fermentable but sucrose and dextrose are. At those potential alcohol levels, you'd need 14 billion cells of yeast at the standard pitching rate of one million cells per ml of liquid per degree plato to properly attenuate the mixture. 14 billion yeast cells is about 1 gram of yeast.
> 
> The reason the outlined recipe for this method is bunk is that one litre of liquid at your pitching rate of 'one teaspoon' of yeast and the specific gravity of liquid is that you'll get about 3-5 days of the smallest amount of CO2 before the mixture has attenuated, or completely stalled. The problem with the gravity is that it's too high and can present attenuation problems for the yeast. Most strains really struggle in liquids over 10% unless aerated periodically. One litre is also WAY too small a batch size. Yeast starters for batches of beer at 1/2 gallon barely add a scent to a closet, let alone add any CO2 benefit to plants.
> 
> ...


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## ultimate buds (Apr 15, 2010)

if youdo try this keep the co2 container slightly higher than the top of you plants as co2 is heavier than air so falls to the ground


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## Wetdog (Apr 15, 2010)

Listen to Homebrewer.

It will be pretty much pissing into the wind and the $$$$ will be better served with ventilation bringing more fresh air (and CO2), into your grow.

It sounds great, but just doesn't work wort a shit. LOL

At least, brew a batch of IPA and get your $$$$ wort.

Wet


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## homebrewer (Apr 15, 2010)

Wetdog said:


> Listen to Homebrewer.
> 
> It will be pretty much pissing into the wind and the $$$$ will be better served with ventilation bringing more fresh air (and CO2), into your grow.
> 
> ...


Wort? Sound like we've got another brewer here. Cheers bro!


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## Wetdog (Apr 15, 2010)

LOL Wondered if anyone (besides another brewer), would pick up on that.

Yeah, I once vented my primary into the grow tent ....... It wasn't worth the effort of moving the carboy from its normal location.

It would have been nice, beer and bud, but just didn't happen. LOL

Wet


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## bigv1976 (Apr 15, 2010)

What up Homebrewer? Ty for the info bro!!! I run 2 1 gallon jugs and freshen them up every week. I am sure you know what you are talking about but I did an experiment. I sealed a 4 day old 1 gallon mix in a milk jug and in 7 minutes and 41 seconds. I have a 2x4x3 growing chamber set up for 8 plants. You dont think that a mix that will explode a milk jug in less than 8 minutes adds a decent enough co2 to my 24 cubic foot grow chamber to be beneficial to my plants?


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## homebrewer (Apr 15, 2010)

bigv1976 said:


> What up Homebrewer? Ty for the info bro!!! I run 2 1 gallon jugs and freshen them up every week. I am sure you know what you are talking about but I did an experiment. I sealed a 4 day old 1 gallon mix in a milk jug and in 7 minutes and 41 seconds. I have a 2x4x3 growing chamber set up for 8 plants. You dont think that a mix that will explode a milk jug in less than 8 minutes adds a decent enough co2 to my 24 cubic foot grow chamber to be beneficial to my plants?


People have blown up glass carboys so I'm positive there is enough CO2 being produced to do some damage to a milk jug. The original recipe called for a 1 litre batch, a cup of sugar, and 1 teaspoon of yeast. That is the recipe I took issue with. In my response, I thought 1 gallon would be more beneficial and two gallons even more so. But I also question the cost-benefit of all that sugar being used each week and the effort of mixing the batch. It could certainly work in a smaller room that is sealed but does it work better than adding an intake fan? To each his own and I like experiments like this. I think you're doing the right thing with your batch sizes and the frequency with which you're changing them. I just hope you find it beneficial.


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## CaptainW (Apr 15, 2010)

Ty everyone for clarifying it for me. Basically wasted effort. I already have a 12in fan pumping air in and a 6in inline fan with a carbon filter pulling it out and another box fan in the back with filters throwing the air around. So the bottle trick would not really help all that much i suppose.

oh and +rep for all thanks


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## homebrewer (Apr 15, 2010)

CaptainW said:


> Ty everyone for clarifying it for me. Basically wasted effort. I already have a 12in fan pumping air in and a 6in inline fan with a carbon filter pulling it out and another box fan in the back with filters throwing the air around. So the bottle trick would not really help all that much i suppose.
> 
> oh and +rep for all thanks


You sure have a lot of air flow in there and I'd doubt your plants are CO2 starved. Plus, if you added CO2 in some way, I'd think it would get sucked out real quick-like.


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## ruudong (Jun 8, 2012)

homebrewer said:


> You sure have a lot of air flow in there and I'd doubt your plants are CO2 starved. Plus, if you added CO2 in some way, I'd think it would get sucked out real quick-like.


3/4 cup suger 1 ts of yiest 6 cup hot water when i say hot not boiling hot u will kill the yeast to cold it wont activate 

i run a small plastic pipe from the 2 liter bottle to a 1 liter bottle 
the piping is only in the 2 liter bottle 2 inch in 
and in the 1 liter bottle the piping is at the bottem just warm water in the 1 liter bottle half full its like a filter system make sure no alcoholl escapes 

the 1 liter bottle has a second tubing again 2 inch in and running to your fan i tape it just behind it the fan takes in the co2 and blows it out 

dont forget to seall up the gaps that u cut out of the twisty cap of the 2 lit and 1 ltr bottles to fit your tubing ,
there u go the heat from the light will activate the co2 u will see bubbles every 5 /10 second from both bottles


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## Gastanker (Jun 8, 2012)

This is a really old post you dug up. But if anyone is interested:

_4. FERMENTATION METHOD OF CO2 ENRICHMENT: 
Sugar is converted into ethyl alcohol and CO2 when it ferments due to the action of yeast. In this method, the following ingredients and equipment are needed: 
1. Suitably sized container, plastic or glass 
2. Sugar, common or invert 
3. Yeast, brewers or bourgelais wine yeast 
4. Yeast nutrient 
5. Sealant, cellophane, tape or lid 
6. 1/4 plastic tubing 
7. 1/4 shutoff valve 
8. Balloon 
9. Starter jar or bottle 
A pound of sugar will ferment into approximately half a pound of ethyl alcohol (C2H5OH) and half a pound of CO2. One pound of CO2 makes 8.7 cubic feet of CO2 gas at normal atmospheric conditions. In our standard 8 X 8' X 8' grow room, you will need to generate 512 cu. ft. X .0013 (1300 PPM CO2) = 0.66 cubic feet of CO2 every four hours. It takes time for the yeast to ferment sugar, so the size of container you should use in determined by dividing the cubic feet of growing area (512 Cu. ft.) by 32 = 16 gallons. 
A convenient container to use here would be a plastic kitchen garbage can. These are inexpensive and easily obtainable. 
To determine how much sugar we need for six weeks of operation or until fermentation ceases, the following calculations are necessary: From the above paragraph, we need 0.66 cu. ft. of CO2 every four hours. If one pound of CO2 makes 8.7 cu. ft. of CO2, we will need 0.08 lbs. of sugar, but because every one pound of sugar only makes 1/2 lb. of CO2, we must double the amount of sugar needed, i.e. 0.08 X 2 = 0.16 lbs. of sugar every four hours. Since there are six four-hour periods in a 24 hour day, the amount of sugar we need is 0.16 x 6 or 0.96 lbs. of sugar per day. 
If we round this off to one pound of sugar per day, we will need 42 lbs. of sugar in six weeks. We must consider that only 80 to 90% of the sugar will be completely converted in this length of time, therefore, we should actually use about 48 lbs. of sugar in six weeks. 
The sugar solution to start with is 2 1/2 to 3 lbs. per gallon. You can use hot water to start with, as sugar dissolves faster in it than in cold water. You must let it cool to 80-90 degrees F before adding yeast to it or the yeast will be killed. Start with the fermenting container only half-full as you will be adding an extra gallon per week for 6 weeks. Begin with eight gallons per week and 24 lbs. of sugar. 
To start the solution fermenting, you will want to make a "starter batch" of sugar water, yeast and yeast nutrient. To do this, use a coke or beer bottle (approx. one pint), dissolve 1/4 lb. of sugar in 10 oz. of warm water (approx. 3/4 full), add a pinch of yeast and two pinches of yeast nutrient to this sugar mixture. Place a balloon on the bottle and set in warm location, 80 to 90 degrees F, for one to two days or until the balloon expands and small bubbles are visible in the solution. 
After the starter solution has begun fermenting vigorously, it is added to the main fermentation tank at the same temperature already mentioned. After a day or so, to see that the system is working properly and that CO2 is being generated, close the valve to the supply tube and, if the unit is sealed properly, the balloon should expand in a short period of time. To regulate the amount of CO2 being delivered to the plants, open the valve until the balloon is only half the size of full expansion. 
The CO2 supply tube with in-line valve should have a 2" loop in it half full of water to serve as an air-lock. This loop can be held in place with tape on the side of the fermentation tank. The open end of this tube can either be positioned in front of a circulating fan or run through "T" fittings to make additional tubes, the ends of which can be positioned above your plants. Remember, CO2 is heavier than air and it will flow downwards. 
Once per week, undo a corner of the Saran Wrap and add an extra gallon of sugar solution and yeast nutrient, then reseal the top with tape. Use three lbs. of sugar and one teaspoon of nutrient per gallon. 
After the last gallon is added, after six weeks of operation, let fermentation continue until the balloon goes down and no more bubbles are visible in the "U" tube. When this point has been reached, taste the solution. If is it sweet, fermentation is not complete and a new starter batch should be made and added to the tank. More yeast nutrient should also be used. If the solution is dry (not sweet) like wine, fermentation has stopped and the alcohol content has killed the yeast. At this point, it's time to clean your tank and start a new batch. 
The fermentation process is quite good for generating CO2 and relatively inexpensive. Regular or invert (corn) sugar is inexpensive and available. You may have to purchase invert sugar at a wine supply store. This method of generating CO2 will cost approximately 50 to 60 cents per day. 
To save money on extra yeast, you can either take out approximately a gallon of fermenting liquid and save for the next batch, or start a second system identical to the first and alternate themóclean and replenish one, then three weeks later, clean and replenish the second.

So to supplement my entire 4x4x6.5 tent I would need ~10 lbs of sugar per grow ($5). To just supplement the 4.5 sq ft that I care about I need significantly less. Three 1 gal brews should easily up this tiny tiny area to over 1500ppm CO2 

Anyone what is using yeast/sugar for CO2 should really read this article (the link) and then do the math. Hydrofarm - Carbon Dioxide Enrichment Methods

*If the article goes over your head here is a simplified formula: 
X*.0013 = Y 
(Y/8.7)13.2=Z 
X=cubic feet of grow room Z = amount of sugar in pounds used per day*

*So if your room is 4x4x8 then you would want to use a total of 0.25lbs of sugar per day. You should either use a 4 gallon container or four 1 gallon containers for this. Start off with 1lb of sugar per container (or 4lbs in the 4gallon) and add an additional 1/4lb per container every 4 days (or 1lb in the 4gallon). This will keep the area at 1300ppm. *_


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## ruudong (Jun 12, 2012)

yep im trying to get my hands on champaine or wine yeast at the moment , just using normal bread yeast at the moment been 2 weeks of constant bubbles at 2 second , when light is off its 6sec a bubble . but i have hose pipe outside of tent when lights are out am i right to do that


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## Dontcough (Jun 17, 2012)

I'm currently using this in my setup, not sure if it's a wasted effort or not but I do know that I can't stay in there too long or else I'm going to get a serious headache. Guess that's a good sign. My ventilation consists of a half opened closet door and 2 shitty box fans one to pull cool air in and the other to blow on the plants for stem growth.


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## yesum (Jun 18, 2012)

Was reading on another site that you can get the benefits of co2 by having a air exchange in you room or tent twice a minute.

Sounds a lot easier.


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