C02 and air exchange in flower

During Flower, on for the first 3 weeks I add CO2 at 1200PPM and gradually reduce it as the. Weeks in flower progress.

So here’s my question, my exhaust fan is off during this time and my temps are let to drift up to to around 85F (cob led running ~1200 micro moles on the canopy) and I do my best to keep the humidity in vpd range in check from the online VPD charts at 80% humidity using a dehumidifier or humidifier depending on the time of year as we get a lot of rain in Washington which affects my humidity a lot in my tent.

I’ve read I should exchange the air after the lights go off which is easy but is there any benifit of air exchange mid flower, say 6 hours into lights on if my temp and vpd are looking good? I’ve read so many diff things I was hoping to get some answers based on true agricultural science. Do plants exhale other chemicals etc that need to be moved away from the plant that in high concentrations in a mostly sealed environment can become an issue such as ethylene? If so, is there a volume of air that should be exchanged every so often and at what frequency?

Thanks guys!

Akira90 said:

During Flower, on for the first 3 weeks I add CO2 at 1200PPM and gradually reduce it as the. Weeks in flower progress.

So here’s my question, my exhaust fan is off during this time and my temps are let to drift up to to around 85F (cob led running ~1200 micro moles on the canopy) and I do my best to keep the humidity in vpd range in check from the online VPD charts at 80% humidity using a dehumidifier or humidifier depending on the time of year as we get a lot of rain in Washington which affects my humidity a lot in my tent.

I’ve read I should exchange the air after the lights go off which is easy but is there any benifit of air exchange mid flower, say 6 hours into lights on if my temp and vpd are looking good? I’ve read so many diff things I was hoping to get some answers based on true agricultural science. Do plants exhale other chemicals etc that need to be moved away from the plant that in high concentrations in a mostly sealed environment can become an issue such as ethylene? If so, is there a volume of air that should be exchanged every so often and at what frequency?

Thanks guys!

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I simply forego CO2 anymore. Other than veg I seen little difference. I run my exhaust fan 24/7. All my co2 comes in from outdoors via my geothermal’s fresh air intake all filtered with a 20x25x5 filter.

It would depend on your source of co2, bottled I wouldn't worry about it, burning NG is fine for most strains, however, more strains seem to be sensitive to burning propane. What propane is, can be different from tank to tank and region to region. So your NOX and other burn compounds from the burn can be vastly different from tank to tank.

I would say look to your plants if they seem happy and healthy then don't do it and waste all that gas. However, if you see a deficiency then try your plan.

Uncle Reefer said:

It would depend on your source of co2, bottled I wouldn't worry about it, burning NG is fine for most strains, however, more strains seem to be sensitive to burning propane. What propane is, can be different from tank to tank and region to region. So your NOX and other burn compounds from the burn can be vastly different from tank to tank.

I would say look to your plants if they seem happy and healthy then don't do it and waste all that gas. However, if you see a deficiency then try your plan.

Click to expand...

Im using natural gas so that’s at least good. Thanks for the feedback!