ventilation when using CO2

Discussion in 'Growing Information' started by inchdeep, Mar 14, 2015.

  1. inchdeep

    inchdeep Registered+

    I have read about everything on ventilating when using CO2. Nobody seems to agree on what to do. I have the CO2 running in my tent and I have the exhaust fan coming on every two hours for 15 minutes dark and light. Temperature and humidity are not problems in New England right now so I don't need to run the fan to control those.
    Some say twice an hour ventilation is right but then you exhaust all your CO2.
    What do I do to get it right.
  2. DTRave420

    DTRave420 Registered+

    I would think you'd either grow in a sealed room or just let the C02 build up again after it's scrubbed every 2 hours...
  3. inchdeep

    inchdeep Registered+

    I do let the CO2 build up after venting. CO2 is off at night. I need to know if venting every two hours is enough.
    Thanks for your response DT.
    • Like Like x 1
  4. DTRave420

    DTRave420 Registered+

    As it should be and not a prob. I was talking about during "Lights On"...
  5. inchdeep

    inchdeep Registered+

    Gotcha. you are right
  6. gardenermendo

    gardenermendo Registered+

    Ok, think about this logically.

    Why are you venting? To get rid of smell? To bring in new air? To get rid of moisture? To get rid of heat?

    The answers depend on what equipment you have, and factors in your room.

    You can use dehumidifiers to lower moisture, and that has nothing to do with venting.

    You can use sealed tubes on your lighting to vent the heat to outdoors. You can use air conditioners or swamp coolers to get rid of room heat. Swamp coolers bring in moisture and lots of air, so you probably need venting for that.

    You can scrub the air right back into the room for the purposes of eliminating smell.

    If you control all of these factors you don’t need to vent much at all. Hence, some use sealed rooms. I don’t have a perfectly sealed room, but I do run these kinds of equipment to control environment. For me, the biggest challenge is controlling heat, particularly during the warmer half of the year.

    If you add CO2, you’re trying to provide more CO2 then the air provides. Plants use up the CO2 in normal air, which is why you have to bring in new air regularly. Or provide your own CO2 and monitor with a guage.

    So it is possible if you’re managing other environmental factors, and you know your CO2 level, you don’t have to exhaust air at all.

    Does this make sense?
    Last edited: Mar 14, 2015
  7. Myrucca

    Myrucca Registered+

    I run my co2 15 min at the top of every hour the lights are on. And at the same time my intake and exhaust are running , I am currently in a green house with record heat waves hitting so cal ATM, I'm thinking since co2 is heavier than oxygen and my co2 halo is hanging from my hood I'm just guessing the hot air rises to my ceiling and gets exhausted through vent while the cooler heavier co2 lingers down below the canopy not sure though.
    You can purchase a monitor to show current o2 and co2 lvls.
  8. The Widow White

    The Widow White Registered+

    Our setup is in a sealed room and we do not vent CO2. I've never had any issues with it before. Don't know if that helps or not, but that's what happens around here. LOL Good luck! Widow White
    • Like Like x 1
  9. Myrucca

    Myrucca Registered+

    Last edited: Mar 15, 2015
  10. inchdeep

    inchdeep Registered+

    gardenermendo,Myrucca and The Widow White;
    Thanks for your responses. I guess I don't have to vent unless heat or humidity get too high according to your posts. Thanks, problem solved.
    • Like Like x 1
  11. irydyum

    irydyum Registered+

    The byproduct of using CO2 is no ventilation necessary. I run the room sealed all day and dump for 15 minutes every 3 hours during lights off. The only reasons to exchange air in the growspace is for expelling heat or bringing in more co2. I have equipment monitoring my CO2 constantly and data logging it, so i can tell you with certainty that ambient levels in my area hover around the 430ppm mark. I can also tell you that if myself and a friend stay in the room talking and working for an hour or so that the levels will go up as high as 1200ppm. You'd be surprised how much we actually can affect a sealed room. In flower I typically run 1000ppm for the entire cycle. In veg where I don't run CO2 the levels don't really drop, but I only have 6" plants or less in there. I've had to run it into the mother room because the levels would drop down to 200ppm, which I have read can slow growth to a crawl.

    I guess the point of all this is to invest in something that can give you some hard data so you know what you're up against. IMHO if you make the investment to run CO2, invest in the devices that will help you deploy it effectively.

    Happy Gardening
  12. James2378

    James2378 Registered

    While you may get decent results by running CO2 and not ventilating your sealed room, you will hit less weight than if you had properly ventilated as well.

    Here is why: Because of a plant biproduct and burn biproduct gas called ethylene. Ethylene known as the death hormone acts at trace levels throughout the life of the plant by stimulating or regulating the ripening of fruit, the opening of flowers, and the abscission (or shedding) of leaves. Excess ethylene will cause your buds to rippen faster in the last few weeks and will stunt your bud growth. Dying leaves in the last few weeks produce ethylene. Burning CO2 creates ethylene as well.

    Plants consume CO2 in the process of photosynthesis and convert it to sugar. Oxygen is a waste product of this reaction, in that water is split to form hydrogen and oxygen. The plant uses the hydrogen to produce ATP. This process is only occurring in the day when there is light. However, at all times, the plant is respiring, just like people. They need oxygen for the metabolic process and produce CO2 as a waste product. Indoor closed grows also produce

    Ethylene . This is a plant hormone in a gas form that can have negative effects on flowering plants { specially when the plants are closer to finish]. Any dying and decomposing plant mater can produce Ethylene.

    Ethylene damage can be hard to see if you dont know what your looking for and can have very negative effects on your yield .Its nice to shut down the ac at night and flush out all contaminants and start fresh every morning. Some people have good success periodically flushing out there rooms of co2 during the day. There is also some discussion out there regarding stimulating the stomata of the plant to open fully after they have slowly been closing and becoming small from large quantities of co2 in the air. But there is a certain logic to it. [why open your mouth wide if you only need a small breath]. personal preference is the answer you seek ,theres no one way of doing anything

Share This Page