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CHEAP "DIY" CO2 Enrichment Generators

Discussion in 'Indoor Marijuana Growing' started by Ganja Guerrilla, Oct 14, 2006.

  1. CHEAP "DIY" CO2 Enrichment Generators

    "SOME PEOPLE SWEAR BY CO2" The high cost of CO2 enrichment setups are costly, so I have researched, tested, played with sodium bicarbonate, vinegar, sugar & yeast and this is as simple and cheap as I can get, to do some testing on the CO2 Injection Enrichment. I have come up with a Do It Yourself CO2 Enrichment Generator, the described set up is an inexpensive way to observe first hand the benefits of CO2 injection on plant growth. I personally had never seen what CO2 could do for a plant before , and would probably never have purchased a conventional CO2 injection system because of the high cost. In fact, I still haven't purchased one. I find the this method adequate for my current needs.

    The first step:
    Find 1 gallon milk jugs , if your doing a closet grow 1/2 gal jugs will be fine as in demo photos. Fill the jug with 6 cups of water (3 cups for the 1/2 gal size), now use a permenant marker and draw a line at the water level (this is the fill line for the sugar water, now discard water in jug). Get a 16 penny framing nail heat the tip of the nail and poke 10 holes in the jug 1 - 2 inches above the water level and in a straight line parallel to the water line (see photos) these are the CO2 gas discharge holes.


    The second step is to create CO2. I mix 3/4 cup sugar, 6 cups water and a pinch of yeast (roughly 1 teaspoon does the trick). The exact ratio of ingredients is not critical. (cut amounts in 1/2 for 1/2 gal use)
    Using the above mixture, I regularly get 10-14 days of CO2 production. When the system stops bubbling (the drop in gas production is often precipitous), dump out everything and mix up a new concoction.

    You can see the active CO2 escaping the surface in the photo below


    This CO2 Generator DEFINETLY WORKS a test has been done on an enclosed generator, connected to a aquarium hose, the other end of the hose in a jar of water,and the gas is emitting at a rate of one bubble every 3-7 seconds under enough pressure to operate @ a depth of 8 inches, a sufficient rate to satisfy my continued testing.
    Now suspend the CO2 generator above the plants (CO2 is heavier than air) as the CO2 is generated it begins to build pressure and fills the plastic jug untill it reaches the discharge holes (the CO2 pressure in the jug keeps pushing the CO2 out the discharge holes)and begins to spill out over your plants.


    Hot water kills yeast. If you dissolve yeast in hot water (like what comes out of my gas water heater), you probably won't get any CO2 from your setup. If you've mixed things up properly, you should get CO2 production within a few hours, possibly more quickly; I've sometimes had things going 30 minutes after mixing a new batch.
    Here's what I do:
    Fill a 2 cup measuring cup with hot water, and dissolve the sugar in it. Add three more cups of cold water to the mixture and mix it up.
    Dissolve the yeast in a cup of cold water and add to mixture. I've only used bakers yeast, but others should work too.
    Add more cold water to mixture to fill to desired level. Cover the gas discharge holes with your hand & Shake the mixture well.
    Let sit at room temperature for a few hours until the mixture reaches room temperature. That's often all the time that is needed to get initial CO2 production going.

    Some batches of yeast take longer get going than others. For example, yeast stored in a refrigerator takes longer to become active than yeast stored at room temperature. Letting the yeast sit out at room temperature overnight before adding it to your mixture reduces the startup delay. Another suggestion (from homebrewers) is to hydrate the yeast in a cup of warm (80 degree) water for 20 minutes before adding it to the sugar mixture

    I am still experimenting with exact ratios of sugar, yeast and water. In my system, the rate of CO2 production is relatively steady for a number of days, but then drops precipitously (from several bubbles a minute to no production in 24-48 hours). I suspect that the yeast exhausts some trace element or other critical ingredient. Yeast needs a number of elements, including nitrogen (e.g., ammonia but not nitrate), magnesium, phosphorous, potassium, calcium, zinc, iron and copper. My initial hypothesis was that a buildup of alcohol limited yeast production. However, a homebrewing friend reports that it would take roughly 3.75 cups of sugar in a 2-liter bottle to produce enough alcohol to reach a concentration of 15%, the point at which no strain of yeast can survive. As another data point, I have been running a mixture now for over six weeks that is still producing an adequate amount of CO2. I have no explanation for the longevity of the current mixture. I used the same general recipe that previously worked for only two weeks.

    It should be possible to culture a new mixture using yeast from a previous batch. Simply save the sludge that collects at the bottom of a mixture. The top layer of sludge, which should be a bit lighter in color, consists of live but dormant yeast cells. The darker layer underneath is dead cells. I have not tried this myself. For more information, look towards the homebrewing field.

    In summary, the described sugar, yeast and water CO2 injection system provides an inexpensive way to experiment with CO2 in a plant grow room. It is particular attractive to those interested in trying CO2, but skeptical that benefits justify the cost of conventional systems. Although a bit more hassle to maintain than a proper tank-driven injection system, I do not find the burden to be excessive. Although I could afford to purchase the more expensive conventional system, I have little inclination to do so at this point. I spend much more time fussing over my plants than I do fiddling with the CO2 Generator rig & frankly I'm still undecided as to the affects of CO2 enrichment, at this time, part 2 of the experiment is to determine actual appreciable enhancement with the use of CO2 injection.
    This is still experimental so you will need to adjust the number and placement of your CO2 generators. If infact I find in testing with these prototype CO2 Generators, that IF THIS IS beneficial I may revise my CO2 generator tank to utilize 4" PVC pipe as in diag below for better dispersement across the grow rooms


    I also believe it best to turn the "Exhaust fans off" during CO2 period so that all your CO2 is not exhausted immediately out of your grow room before the plants can benefit from the CO2 enrichment. the lites also need to be ON when you turn off the fans this is the optimum time to utilize the CO2 during photosynthesis. and lastly I also believe that the plants may now need a bit more nitrogen to keep all plants growing at full steam with the increased growth demand from the CO2.
    This Co2 enrichment system is very easy and cheap, I'd be interested to hear any results any of you find, if you decide to try the experiment "SOME PEOPLE SWEAR BY CO2" we shall see?
  2. Nice thread Ganja, It is quite long and i admit i only read the first 3 paragraphs. Here are my thoughts about it tho, great info, but there is an easier way to do this, i have 4 CO2 generators in my cabinet, they are made from 2 liter soda bottles instead of milk jugs.

    In the 2 liter bottles add:

    2 cups of warm water (not hot, high heat kills the yeast)
    2 cups of sugar

    Close the cap on the bottle or jug of your choice and sufficiently mix the sugar and water, a half cup of water or so may be necessary to dissolve the sugar. Then take the cap off

    1 teaspoon of active yeast

    Recap the bottle and mix the yeast into the sugar and water. Then using a drill or a hot nail like Ganja, make a small hole in the top, not a pin hole, but you dont want it to release the prescious CO2 too quickly, i found a quarter inch hole is about perfect.

    The bottles will last 2-3 weeks, mine are coming up on 3 weeks and still going strong.

    The one problem i found in your post tho ganja is that you said to hang the bottles over the plants, i do not reccomend this, dropping a jug on plants could be tragic, dropping one on your lights could be extremely expensive.

    I have them all around my plants, as close as i can get them, i believe in a perfect world i would have clear hose from the bottles and attach it up the base of the plant and have it follow up the stem of the plant to direct the CO2 right to the leaves! i havnt yet done this yet, i do plan on it and ill come back with pictures one i achieve success.

    To go with added gasses and not to jack your sweet thread Ganja Guerilla, but oxygen is also a key to plant growth, not to the leaves, but to the roots. Adding some gravel to the bottom of your pots and then adding a simple air pump and pumping air into the bottom of the pot into the bottom in the soil can drastically decrease grow time. If you want more info on it, i can find the thread i found a couple weeks ago which is full of diagrams! If not ill edit this part and get rid of it!

    kisses Ganja Guerrilla!
  3. Nice thread, 5* +rep

    What would be interesting tho, place a large bag over the top of one of the CO2 generators and capture the CO2 over a day or two just to see how much CO2 is generated with this solution.

    Also could the collected CO2 be used to kill a pest infestation on a single plant (If the bag was full) by placing it over the infected plant. Bugs need air and the CO2 would suffocate them.

    Just an IDEA ?
  4. I dont see that working at all, heres a few reasons. You would have to seal the bag around the plant and the pot, also plants produce oxygen. Thr air thats breathed in by us and those bugs is only about 17% oxygen to begin with, so they could probably survive however long the CO2 lasted because they dont need much oxygen to survive.

  5. yeast at the grocery store? (may be dumb ass question)
  6. yep any grocery store, they keep it right next to the flour and sugar and other baking stuffs.
  7. baking yeast, is what Im testing now, but brewers yeast will work
  8. Awesome thread, I'm glad you're researching this. I also plan on making my own CO2 generators with milk jugs. What I'm thinking is (like deafeningsilanc) drilling two 1/4" holes in the lid of the jug and running 1/4" OD poly tubing up the wall and hanging over the plants.

    I hope you keep us updated on different mixtures you've tried and the effects you've gotten from these generators.

  9. Im definately going to try this. I've got 4 plants in a cab that fits perfectly 4 so im gonna make a stand, have the bottle sit on it right in the middle of the 4 and see if it does any good! :D 3 weeks into flowering hopefully this will benefit!
  10. Way cool thread, +rep
  11. I tried the yeast and sugar technique to enrich the CO2 in my closet. It only increased my closet's CO2 level 100ppm from what is normal air being pumped in (about 450ppm at my house). It did stink up the grow, but just because it stinks does not mean its working. I did a one gallon mixture of yeast and sugar first, then I tried two gallons. I was not able to get near 1500-2000ppm needed. I now run a closed system with no ventilation unless temps get above 85, there is no way yeast could supply enough CO2 in a closed system. I feel if it cant realy kick up the CO2 levels in your grow, dont even bother. Fresh air works great.

    I use CO2 in my closet grow and it does make a noticable difference. I looked into all the options before going with 20 pound tanks ($12 to fill). Sugar and yeast seemed to be a messy waste of time, CO2 generators (burning natural gas in your grow to make CO2) is more expensive then tanks and makes heat. I don't like the idea of burning anything in my grow.
    I have some money saving tips for setting up CO2:
    I found this CO2 controller for $165 Honeywell Carbon Dioxide Sensor and Controller

    They sell them every day on Ebay. Link to the Honeywell Product Specifications.
    Call every welding supply store in the yellow pages and ask how much for the tank and what a refill costs. You can try home brew stores as well, but I found them to be twice as much. Get the tank solenoid at the welding supply or an aquarium supply store. Hydro stores will bump up the price of a tank solenoid 300% . I put one together for $33 (solenoid, bubble counter, plumbing, gage, and extension cord.)

    If you like low tech: Buy that controller and a tank. Crack the tank open and let it leak. Use the controller's read-out to adjust how much to open the valve.

    I use two 20 pound tanks for a complete grow. I keep the PPM at 2000. No matter what anyone says, too much CO2 wont kill your plant. I had a bad valve and my whole tank drained out over the weekend. The plants loved it.

    Some shots of my CO2 setup.

    I don't want to be a buzz kill on this topic, but both my CO2 meters showed only slight gains using the home-brew method.
  12. I found this to be a very good read regarding CO2 generation..


    It goes into great detail about the many methods of generating CO2 for a grow room.

    Info Like This
  13. I use my own Home brewing kit to feed my plants Co2, I don't have a Co2 meter or anything to check but when I first started using the Co2 from my brewing barrel I saw the difference in my plants in a matter of 2-3 days.
    I don't think the Sugar, water and yeast method works well enough to make a difference, one of my fellow growers was using that method and after 10 days with no noticeable difference he started using Home Brew as well.
  14. I thought the home-brew method was the sugar and yeast.

    Max11 has put it all in a nut-shell
    I think it will cost less to fill a tank from the welding supply, rather then making a 16 gallon tub of stink juice :) . CO2 by the tank is clean and compact. It has the rep of costing alot. After you own the tank (ebay), it will cost you $12 to fill.
  15. You know not all grow rooms are 8' X 8' X 8' so I guess it's very room size dependant. If you were to direct the small containers directly onto the plant it will have some beneficial effect but I'm not sure.

    IMO the bottle and controller is the way to go for bigger grow ops but for the small grow with one or two plant the small container will be effective, just not quite sure how much. I'm gonna do a small experiment with the containers just to see if it has an effect.
  16. Hey Rump or anyone who would know I was wondering would something like this work for regulating and knowing how much CO2 is in the air? CO2 Regulator Tap Rite,Beer Soda I am planning on using a closet 8 feet tall 5 feet wide and 2.5 deep. I am planning on doing an enclosed environment for mine so I need CO2...
  17. yeah, small closed spaces can greatly benefit from Co2 enrichment, even if it's a makeshift thing. i used two containers with a liter and a half of lukewarm water two cups of sugar and a three quarter teaspoon yeast, in a 2.5X2.5 foot closet, with sixteen vegging plants. noticable increases in leaves size within a several hour period and no ventilation or air circulation whatsoever, suggested to me the ffectiveness ofthis method. the bubbling was quite rigorous for over a week.

    since then, it has been a while.. i haven't gotten it to work several times, and gave up eventually
  18. Hi good guide but can you get the photos to work. I'm more of a visual person
  19. I think if I can get it done cheap enough($100-$130) I Would rather do it with a CO2 tank. From my understanding I just need the tank and something to count the ppm of the CO2 in the room. I can adjust the tank to get to my desired levels? Is this right?

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