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Cultural Healing and Life

The Indoor Garden Environment - Part 4 - Air Quality & CO2

JJ the Gardener

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The Indoor Garden Environment

~A Cultural Healing and Life Compilation and Writing.




Air Quality

Air Scrubbing

Air quality in grow rooms is dependent on several factors but most important for plants is co2, temperature, humidity and air flow.  However, we often do not think of the other aspects of air such as various particles such as pollen, hairs, dust, smoke, dander about anything than can float in the air. 

When considering I recommend a charcoal filter rated for the size of your room or slightly smaller than your rated CFM and run independently of any exhaust filter, Place the fan directly on top of the filter and secure to filter.  Allow fan to filter air blowing the air upwards. 

The higher position the filter the better but keep away from moisture and humidity of 80% or more as it will stop the effectiveness of your filters. 

  • This is operated in the garden and separate from the exhaust system or you can run dedicated air cleaning machines.
  • This will add some heat from the fan into the room
    • Account for additional electric needs.

To "scrub" the air take a filter for the size of your room or one with a lower CFM rating and do same with the size of the inline fan ensuring to match the correct size fan to filter. 


Aspects of air scrubbing:

  • Offers a higher degree of smell containment when used in conjunction with a traditional charcoal smell filtration system or any other effective smell management system.
  • Cleaner air in grow room.
  • Can remove gas created by end of life leaves which give off a gas that encourages ripening.
    • This is stated that it can be used to extend ripening times for some crops.
      • I personally would not consider as a base justification as I would tell you to remove the dead and decomposing leaves.
        • I do not necessarily believe this but it is stated in several competent writings.
  • Down side to blowing into the room is that it can distribute a fine charcoal dust from the filter.
    • A solution is use a lung room and scrub the air through that mechanism.
  • I do not find it normally necessary to scrub or clean grow room air but I find beneficial in following scenarios.
    • Consideration for high pollution areas.
    • Additional layer of smell protection when used together with other smell management systems.
    • Consideration for extra protection in breeding setups and will discuss such aspect in future breeding setup writings.


Video on Air Intake


A good example of the construction of a good air intake filter.


Ozone Air Scrubber Option

  • I do not recommend ozone for sealed or closed rooms as ozone is not healthy for plant life or most life in general.
    • Plants will negatively respond that is a exposed to ozone.
  • I have no problem with ozone being used for air filter system that is safely exhausted.


Carbon Filter (Smell)

  • Often carbon filters are used as part of the exhaust system.
  • Adjust for loss of CFM when determining fan size, approximately 25%
  • Replace approximately once per year.
    • Some filters you can switch the cap and extend the life cycle of the filter.
  • At 80% humidity carbon filters are no longer effective.


Carbon filter Video



Air Scrubber Summary

The quality of the air is something we generally take for granted as being a given.  It is not a necessity and adding more noise and heat to your garden area may not be the smartest move but it is an option that should be considered and ruled on as a matter of competence.  In my view, if you can do it, do it.  If you do, use it intelligently drawing and pushing the air in locations such as areas that receive little wind/breeze or are heat sink/spot areas as to distribute evenly throughout the room.

It also can offer an extra layer of smell protection when used in tandem with a tradition smell management system.  This option is also useful in areas of processing where extra filtration may temporarily be of value.  I do recommend to run filtered air in areas that processing takes place in.  This extra is more than a security measure it helps filter any animal hair, pollen or any matter that may be undesirable and visible under a microscope.  For example, when a dispensary is analyzing your crop.  Well filtered air is a blessing in preventing embarrassing detritus in the crops.

Regardless of ones view of this, it is a tool that can easily be employed and should be considered and ruled any time an applicable scenario presents itself for its use.




Carbon Dioxide or C02

Carbon Dioxide is one of those tricky subjects that is easy to misunderstand.  Generally, CO2 is a great a marketing aspect for indoor garden suppliers but what is not often said is how to effectively use them.  I believe many gardeners misuse or they are not efficiently using CO2.  In the end this cost money and is wasted resources.

When using CO2 it is best to be used with "best practice" along with "best practice" in lighting, nutrition and management.  Then the capabilities of achieving the most from your genetics become a possibility.  If not done to effective levels of competence with all other aspects of the plant the reality of the benefit of CO2 is greatly diminished.  Thus, CO2 is only a viable option for flowering for those with well constructed rooms as to maintain efficiency levels in particular in reference to financial costs.

However, it is beneficial to add higher levels of C02 in early veg, cloning stages as the required PPM is far less and this can assist with maintaining heat and light tolerance. 

  • This can be beneficial preparation in the stages before hardening rooted plants off outside or for other needs.
  • Can be a benefit when you ship clones to help them endure shipping as they are stronger.

High Concentrations of CO2 is bad for people and animals and can kill when it reaches 1% of the air.

  • Gardens use approximately 0.15% of the air.
  • However, use a CO2 meter to ensure that no malfunction of a burner and compressed tank could cause a disaster.
    • never saw nor heard of this happening but lets not be a first.


Using CO2

  • CO2 is heavier than air.
    • Thus we put CO2 so that it falls or "rains" CO2 down on the plants.
    • Evenly distributed
      • Small fans strategically pointed upward can keep CO2 in air and over plants and helping distribution.


  • "Best Practice" is to have the grow rooms at optimum levels of C02 during the day.
    • Often CO2 is run in closed rooms.
    • Often 15 minutes co2 dose and then 15 minute air exchange and repeated throughout day cycle.
      • With this setup you often run air cooled lights.
        • Exceptions can be with lung rooms and recirculated air system.
          • This is a trade off in cost efficiency where you run the CO2 at optimum levels throughout the day and replenish as your plants use.  Often used in conjunction with a CO2 Meter/controller.
        • Their is no benefit to running C02 during the night/dark period.
          • Will turn your plants yellow.


  • Seedling, Cloning, initial transplant cycles you only need 300-500 ppm.
    • Few leafs and little photosynthesis.
    • Raising temperature at this level will not help
      • CO2 at this level will assist with plant tolerance to heat and light stress.


  • Vegetative stages after rooting increase CO2 to 600-900 ppm.
    • As plants increase in leaf and growth they will use more energy/photosynthesis and sugars are made.
      • Adjust/Rise the CO2 levels accordingly.
        • It is not harmful to the plants if PPM's are higher than normal for period.
          • This increases the cost of your grow to have ineffective CO2 ppm amounts.
          • Do not raise temperature in vegetative area as in later flowering period.
            • The plants can become more hardier to withstand light intensity and higher temperatures.
              • Is generally part of a CO2 garden operation to treat at this stage as to prepare for the higher temperature and more intense light in a flowering/blooming or an outdoor environment.
                • Helps reduce shock in this regard.


  • Flowering stage keep CO2 at 1000-1500 ppm.
    • Increased growth and bud production by running CO2 during the first 2-3 weeks of flowering.
      • Once flowering has truly begun CO2 may or may not be effective.
        • Their are strong views for and against continue or discontinue CO2 at this time of development.
          • Traditional CO2 use would finish 2 weeks before harvest approximately.
            • I have no direct experience with CO2 in terms of comparison as above.
    • Raise temperature 85f (30°C) to 95f (35°C) for full benefit of CO2.
      • Watch for heat stress in plant and adjust temperature accordingly.
      • You potentially lower your lights towards the canopy if desired paying attention to light bleaching aspects.
        • Plants become more light tolerant with higher CO2 PPM and higher temperature.
          • Helps reduce shock in this regard and allows for leafs to function at brighter and hotter temperatures than normal.


  • Examples of Setups with Enough Light for CO2 Injection up to 1500 PPM
    • I like full spectrum light in addition to brightness, traditionally they go by brightness.
      • 3' x 3' space - 600W HPS or HPS/MH Combo or LED/full spectrum & bright
      • 3.5' x 3.5' space - 2 x 400W HPS or HPS/MH Combo or LED/full spectrum & bright
      • 4' x 4' space - 1000W HPS or HPS/MH Combo or LED/full spectrum & bright



CO2 Garden Options

CO2 Generators and Compressed CO2 are the most effective and efficient ways to add CO2 to your garden area especially for flowering areas.  Vegetative areas also benefit but a due to the less amounts needed this can be actually achieved by other means than generators and compressed tanks. 

It is possible to use fermentation kits and CO2 bags purchased from a store, however this is costly.  If you are seriously into making wine you can also do this if fermentation concentrations are sufficient, smaller areas.  Also for those who live on a farm and/or those who make ethanol, the fermentation process releases CO2.


CO2 Generators & Compressed CO2

  • CO2 Generators often run on propane or natural gas.
    • Some generators are optimized for higher elevations
  • Compressed CO2 is run with a regulator and bottle setup.
    • Costly operationally
    • I like best for:
      • When needing fast increases of CO2.
        • Bug infestation.
        • Management option.
    • When testing CO2 in your environment before dedicating to it.
      • Low initial cost and is often consideration for a "trial" run to evaluate before dedicating to a burner system which may require some room alterations.
        • In some garden situations I like burner systems and the use of a CO2 tank in certain situations.
          • Tank being largely used in supplemental aspects and certain situations.


Very good informative video


Good example of Compressed air system.


CO2 Burner Information, Not an endorsement, for illustration purposes.  I have no opinion on quality.


Set up for this style of burner to give illustration of setup understanding.



CO2 Summary

CO2 use is ideal for most growers only in vegetative stages due to the low PPM requirements and benefits in preparing the plants for follow up stages.  Often smaller gardens will use a bucket or bag CO2 product and hang high as CO2 is heavy and will fall.  Fans pointed up will help keep CO2 in air column.  The costs of these products can be high and some home brewers may be able to devise a system to take advantage but for most this aspect is a pain the ass.

CO2 compressed tanks are a better alternative to the bags due to the low PPM in veg the cost efficiency of tank is more attractive and bags and buckets take up space and are generally a pain the ass.  I recommend only for trial purposes.

Dedicated gardeners with closed systems can create systems that take full advantage of the CO2 and to do this requires a degree of best practice aspects all around.  The average gardener can not easily achieve this no matter what marketing says.

Additionally their is much debate with merit on both sides for and against continued CO2 use after flowering/fruiting has begun.  I have no experience with this aspect and will update as more information becomes relevant.



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