C02 in a non sealed room.

[drgr33nuk]

I found an article written by Ed Rosenthal

"Plants in brightly lit gardens will experience an increase in growth until the level reaches 1,500-2,000 ppm CO2. However, it is difficult to maintain a level much higher than 1,500 ppm unless the space is sealed against air leaks. Some growers shut off the CO2 during the last two weeks of flowering because the plants aren't growing that much and it may affect THC production at the end of flowering."

He doesn't go into any scientific reasoning for this though. I'd really like to hear a botanist explain what they are referring to.

I disagree and never would run my rooms that high. 1200ppm is a much safer number

 

[Rollout]

You get drastically diminishing returns with CO2. Going from ambient (usually around 300 ish) to 1000 ppm gives pretty big returns, but going from 1000 ppm to 2000 ppm will only result in minimal returns. Just so you know, most knowledge in the weed growing community isn't very scientific. There are a huge number of well known "facts" about growing that aren't accurate at all due to this unscientific tendency.

 

[acridlab]

the negative reports are based on ethylene displacement, which can occur with high levels of co2 in later stages of flower. basically, u can end up with large buds with little trich and thc content.

 

[Fatboyjay]

the negative reports are based on ethylene displacement, which can occur with high levels of co2 in later stages of flower. basically, u can end up with large buds with little trich and thc content.

This is basically what my boy told me. He said some chemical (I can't remember) that the plant produces that makes the thc and crystals really pop in those last weeks can be stunted by c02 because the plant still wants to grow rather than ripen.

Since this thread I've tried to find a scientific explanation online buts it's not easy to find. I did find hot nude chicks pretty easy though.

 

[Asslover]

This science is not in an explanation somewheres, it's right here on the boards from experience. Myself and others run perpetual co2'd rooms without issue. Been growing for YEARS and i remember when i wasn't sealed or co2'd and i can tell you from EXPERIENCE that plants have no issues ripening nor does trich/thc suffer.
Look around the boards, there are THOUSANDS of us running sealed co2'd perpetual grows.
Those articles were written at a time when growing was still very much underground and people would take what they read as bible an never question it. If "so & so" said it then it must be true...

 

[drgr33nuk]

This science is not in an explanation somewheres, it's right here on the boards from experience. Myself and others run perpetual co2'd rooms without issue. Been growing for YEARS and i remember when i wasn't sealed or co2'd and i can tell you from EXPERIENCE that plants have no issues ripening nor does trich/thc suffer.
Look around the boards, there are THOUSANDS of us running sealed co2'd perpetual grows.
Those articles were written at a time when growing was still very much underground and people would take what they read as bible an never question it. If "so & so" said it then it must be true...

I think there's truth in what's being said but the changes being discussed are minimal and would not even be noticed by the average smoker. If you have had strains that you have mastered you may notice a decline in potency.

 

[the gnome]

I found an article written by Ed Rosenthal

"Plants in brightly lit gardens will experience an increase in growth until the level reaches 1,500-2,000 ppm CO2. However, it is difficult to maintain a level much higher than 1,500 ppm unless the space is sealed against air leaks. Some growers shut off the CO2 during the last two weeks of flowering because the plants aren't growing that much and it may affect THC production at the end of flowering."

He doesn't go into any scientific reasoning for this though. I'd really like to hear a botanist explain what they are referring to.

here's another that posted recently citing ed rosenthal
https://www.icmag.com/ic/showthread.php?p=6435877#post6435877

Studies have shown optimal growth and yields at 90-95°F, 1,500 ppm CO2, 45-50% relative humidity, 7,500-10,000 lumens/square foot of light, and vigorous air movement both above and below the canopy. CO2 enrichment under 80°F, under 7500 lumens/sf, or above 50% humidity is not recommended because plants will not be conducting photosynthesis quickly enough to benefit from the enrichment.

not knocking Ed, but his work is very dated at this point in time. and much of his findings need to be taken with a grain of salt.
freedomn trail swears by Ed
you can find pics of freedoms results in the link using Eds guidlines,

and mine using 900ppms with much lower temps...