Homemade CO2 Generators for small grows

[badugi]

krazycure, thanks for posting here and please try to not take offense at my disbelief.

You mentioned the strain was a ML cross, and I'm wondering if it's safe to assume an auto-flowering, from-seed plant? As in, not clone? How large was your sample size in comparing? For instance, was it just one seed grow w/ CO2, and another w/o? Or was it a larger number of grows, particularly with CO2 used in the later grows? Could you not attribute better results through, at least: 1) luck [from seed] 2) better skills @ growing 3) other environmental differences?

I also notice the larger plant in the "side by side" picture is in a larger pot than the smaller plant.

Another is that not all plants, cannabis included, have similar CO2 enrichment & ideal environmental requirements as the ones mentioned in the article your posted.

 

[krazycure]

Nope, take a closer look, same pot, just turned to the side because the plant grew at the opposite photo-taking angle. They are both in 1.5 gallon.




As for your other criticisms:


You mentioned the strain was a ML cross, and I'm wondering if it's safe to assume an auto-flowering, from-seed plant? As in, not clone?

BOTH TRUE

How large was your sample size in comparing? For instance, was it just one seed grow w/ CO2, and another w/o?

This was the 5th grow of the SNL gen 2's, with only the first grow as a seed run. In every grow, there was one large area with CO2 supplement, and one small area with no CO supplement. In each grow, from the resulting seeds of the first seed-run, the CO2 enriched cab has yielded better, looked better, and just been all over more vigorous. The non CO2 grows fine, it just doesn't have the OOMPH the CO2 cab does.


1) luck [from seed] 2) better skills @ growing 3) other environmental differences?

1. Maybe?
2. Doubt it. It's down to a science now with AF
3. I don't know what else. They receive the same amount of lumens per square foot in each cab. They are both fed Green Light Super Bloom. Both HPS. Both Miracle grow moisture control soil. Both in same room (but different cabs), both with the same CFM being blown through them.


And the article was just for reference. Take from it what you will.

 

[messn'n'gommin']

From all that I can gather, for now, it would seem that regulated, bottled co2 enrichment has higher initial startup costs than the fermention method, but long term, is the more cost efficient process. Although, the size of the grow would definitely need to be taken into consideration, the fermention method may be worth it to cash-strapped small cab growers. Off-hand, I would say most co2 guys already know this stuff, but it is new to me!

I usually don't copy and paste from other sites (copyright law stuff), but thought this worthy enough to chance. You can find the complete article here:

"Carbon Dioxide Enrichment Methods," by Roger H. Thayer
http://www.hydrofarm.com/articles/co2_enrichment.php



2. COMPRESSED, BOTTLED CO2:

This is the second most popular method of CO2 enrichment and provides fairly accurate, controlled results. Compressed CO2 comes in metal containers under high pressure. Small cylinders contain 20 lbs. of compressed CO and large tanks hold 50 lbs. Pressure ranges from 1600 pounds per square inch to 2200 PSI.

To enrich available CO with compressed gas, the following equipment is needed:

1. Tank of compressed CO2

2. Pressure regulator

3. Flow meter

4. Solenoid valve, (plastic or metal)

5. Short-interval 24 hr. timer capable of having an "on time" variable from one to 20 minutes.

6. Connecting tubing, fittings and adapters

PRESSURIZED CO2 ENRICHMENT SYSTEM ARRANGEMENT

This method allows for the injection of a controlled amount of CO2 into the growing area at a given interval of time. The pressure regulator reduces the compressed gas pressure from 2200 lbs./square inch to a more controllable amount (100 to 200 PSI) which the flow meter can handle. The flow meter will deliver so many cubic feet per minute of CO2 to the plants for the duration of time that the solenoid valve is opened. The timer controls the time of day and length of time that the solenoid valve is open.

To operate this CO enrichment system in our standard 8' X 8' X 8' grow room area, we want to add enough CO to increase the near depleted level of 200 PPM to 1500 PPM. We must then add 1300 PPM of CO2 to a volume of 512 cu. ft. We would like to do this in intervals of time relative to the natural air exchange rate (leakage rate) to keep the CO level near the 1500 PPM range.

Let's select an injection time interval (CO2 enrichment time) of every two hours. First, we must determine how many cubic feet of CO2 must be added to 512 cu. ft. of volume to increase our 200 PPM to 1500 PPM. To do this, multiply the room volume of 512 cu. ft. by .0013 (1300 PPM) to obtain 0.66 cu. ft. of CO2 that is needed. Set the regulator at 100 PSI and the flow meter at 20 CFH (Cubic Feet per Hour) or 0.33 cubic feet per minute. If we set our timer to stay on for two minutes every two hours, we will get the 0.66 cubic feet of additional CO we need to bring the CO level to the 1500 PPM optimum level needed.

Each pound of CO compressed gas contains approximately 8.7 cubic feet of CO gas at atmospheric pressure. Compressed CO2 costs around 50 cents/lb. at most supply houses. At that rate of 0.66 cu. ft. every two hours for 18 hours per day, this method will cost around 30 cents per day to operate. The timer should be set to deliver CO2 during the "on time" (daylight time) for which the lights are set. This is the only time the plants can use CO2; they do not use it when it's dark.

The compressed gas method of CO enrichment has the advantages of fairly precise control, readily available equipment ($150.00 to $300.00 average cost for an installation) and it does not add extra heat to the growing area. It also works well for small growing spaces and after initial equipment costs, is not expensive to operate.

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.

(I haven't read this one all the way through yet, but decided to avoid a double post by including it. Note: this link is an automatic download page.)

“Effect of co2 Enrichment and Light,” HortTechnology Oct-Dec ’98 8(4) [auto-download]
http://www.imok.ufl.edu/veghort/docs/physio_121202b.pdf

(These two links for abstracts that deserve attention. Especially the second one!)

Evidence for increased soil carbon and nitrogen accumulation under co2 enrichment (abstract)
http://escholarship.bc.edu/dissertations/AAI1411120/

Effects of co2 Enrich. on Leaf Chemistry and Repro. Of Twospotted Spider Mites (abstract)
http://www.ingentaconnect.com/content/esa/envent/2002/00000031/00000004/art00005

Namaste, mess

 

[guest1ab]

Where the hell do they get these numbers?

Especially considering that these calculations consider time?

So you've got an 8'X8'X8' room...Okay
And you're aiming at 1300 ppm CO2. I'm with you so far...
1lb CO2=8.7 cubic feet .. OK
You've got 512 cubic feet in an 8x8x8 foot room .. OK

1300/1,000,000 = 0.0013

ok fine so you want 1300 ppm. Considering we're talking about a closed system though, how are you supposed to calculate the absorption rate or whatever?

All of this just seems really arbitrary, unless I'm missing a "per hour" somewhere.

Consider:
From the information given, 6 weeks of operation from 1lb of sugar yields 1/2 lb of CO2 or 3.35 cubic feet. Divide 3.35 cubic feet by 1008 hrs (assuming a constant rate of distribution) that gives you....0.003 cubic ft./hr.
So if you need 0.66 cubic feet/hour (for some undisclosed reason) in an 8x8x8 ft. room, you would need approximately 220 lbs. of sugar. Is that the same number you got?

Also I'd like to know ... why is 4 hrs. the magic number?

I'm confused.

 

[purpledomgoddes]

http://www.icmag.com/ic/showthread.php?t=108618
same general low tech method. discussed here. debatable there too. no harm can come to garden w/ low-tech, cheap methods. gardener-specific though.

hope this helps!

 

[sparkjumper]

Its funny you mention an 8 ft cubed room with co2,thats exactly what I run.Listen to the man the says co2 without a controller is useless,I learned that from years of using a generator.I used whats called a cyclestat for a couple years,it turns the generator on and off according to cubic ft room size.It doeasnt take into account the number of plants or what stage of flowering they were in.I got decent harvests but was missing the true co2 enrichment.I used the syringe co2 testers to verify huge fluctuations throughout the day.Another words,they were growing normally as if no enrichment was present.This changed immediately when I switched to a controller.Set at 1500 PPM,it never fluctutes more than 200PPM which is necessary.If you are growing in a sealed room with uncontrolled co2 enrichment your results will be as if you are flooding the room with fresh air basically,they will grow normally.They wont grow enriched

 

[DIRT DIGGLER]

great thread krazy...

 

[smoke1sun]

hey krazy great lil tutorial. I love seeing DIY'ers hard at word. This seems like a great way to add a lil extra co2 for those of us with less than stellar ventilation.

K+

OLD THREAD DUHHH still good tho

 

[bugasman]

I wonder if I can use this setup to my PC micro-grow. Maybe I will try. Instead of a 3.5 L bottle, I will use 500 mL.

 

[alphacat]

One more head's up for anyone running hydro and thinking about this: make sure your reservoir is insulated from the CO2 supplementation, because if it condenses with the water it forms carbonic acid which will spike your pH down, big time.