Using CO2 in your grow tent

When using CO2 in your tent do you still use your exhaust fan? Also do you use the CO2 during the whole grow cycle or just during flowering?

A grow tent is not a good enough environment to run a partial pressure of CO2. If asking in the context of using ‘exhale bags’, they are a complete waste of time and money.

For CO2 to be effective you need:

-A sealed grow space
-Environmental controls to manage high humidity and temperature
-Double the light needed to grow conventionally (1,500 µmol)
-Gas monitor to maintain correct partial pressure
-Oxygen to root mass to prevent suffocation of the plant

If you don’t have all of these in place it would really be a waste of time to try to deal with it. Also; most dedicated CO2 users run their plants in some kind of hydroponics so they can push insane nutrient loads.

In short you don’t need it to grow good cannabis. If you are technically-minded and have a large budget then CO2 might be for you.


I got a free bag Enlighten Co2 used it found out Fungus Gnats LOVE IT had a battle royale killed hundreds. Took bag out per suggestions from others no fungus gnats


WOW. Thank you so much for your input. I will not be using co2. I have enough to worry about without it.


Not worth messing with

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If you want a cheap,quick, easily replenished source of CO2. Check out your local grocery stores, ask for dry ice.

It helps cool your space, adds about 3-7% RH (dependent on Temperatures; hot less humidity, cool more humidity), and you only need about $5 worth every 5-7 days.

Two ways of use:
1.) hang in front of your fan, to allow airflow across the slab.
2.) take a 1 gallon or higher jug with screw on lid. Drill hole in top of lid for size air hose you’d like to use (make sure it’s snug). Add an epoxy around hose and hole in lid for air tight seal. Run hose to air source above canopy for best results.


add on top 2.) last post

Add 1/4 gallon - 1/2 gallon of water to jug. Place dry ice in water and cap. CO2 source.

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Have you had success with this technique?

This is my main way of applying CO2 to my smaller rooms. I love it, you will want to do the (add to gallon bucket method) for better regulation of CO2. If you place in front of the fan you’ll get a heavy dosage of CO2 in the room.