co2 questions


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Aug 4, 2009
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I am starting to think about adding co2 to my rooms. I have a Mother/Veg room 9.5' X 9.5'. The two flower rooms are 9.5' X 7'. The rooms are sealed. I have 4 1000W lights in each flower room. They are in the fat raptor hoods so its basically a ceiling of glass above the plants. Puts me at about 8,421 lumens per sq ft.

When I install co2, I will have motorized dampers that take advantage of the killer exhaust system already installed.

My questions are

Do I have enough lumens for co2?

I was told I really only need co2 in the last half of flower. Is this correct? Or should I install co2 in both flower rooms?

I really like the idea of tanked co2. The idea of a burner scares me a little bit. I understand a burner is cheaper. Anybody have good experience with them?



Nov 23, 2009
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If you have a nice sealed room you seem set to go. You want to raise temps a bit when using.
I would do the tank. Co2 through out whole cycle

Good luck :)


Nov 25, 2011
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And another "Thank you" to NCH for this insightful post. It takes time to write something as involved as this post you posted, and I, for one, appreciate your effort here. Great read for all including me. I learn something new everyday I read from these forums.
I have a medium sized grow: 96 plants in flower, in 4 zones to have a different nutrient strength/mixture per zone with each zone a 2 week period. I harvest 24 plants every 2 weeks and immediately replace with clones that are +/- 4 weeks in Veg. after healthy roots have been established. Strictly Hydroponics all the way from cuttings to harvest.
I started utilizing CO2 a few years back. I switched from bottled to a propane generator a year ago and have seen several major changes to my growing regime. Firstly, (IMHO & research) Daylight (11on/13off) temperatures can go up to 95 degrees without heat stress BUT is strain dependent more than anything else. Noticeable increase in both Veg. AND bud formation, size and density. Obviously beneficial in both stages. I haven't tried the bug eradication aspect yet due to the heat issues. I have several air movement systems: (1) Emergency evacuation: Two "Whole house" ventilation fans. One is in the center of the ceiling and one at the gable end to the outside. Being the exact same fans, they are wired in "piggyback" style installation which quadruples the CFM's and can evacuate the entire 4226 Cu. Ft. of air volume in less than 2 minutes. This only goes on when the temperature exceeds 95 degrees and is independent of any controllers, etc.. Circulation fans: Four oscillating - 16" wall mounted fans, located 7 ft. above plants in the four corners of the Bloom room. These are "on" when the CO2 is and only after the temperature reaches 70 degrees. Room Circulation: takes the heat from the nursery (separate room) and discharges it into the main (Bloom room) for extraction to the outside along with the main room's hot air. Controls are: C.A.P. AIR-4 with the PPM-4 monitor. My ceiling height is 8.5 feet and the CO2 is almost out of reach from this fan, but I also have a CO2 Circulation fan: a 6" "whisper fan" located on the floor (spaced 2-1/2" above the floor) and directly below the generator. This aids in pulling the CO2 off the floor, up into the main air current, for re-circulation into the canopy. System works quite well and keeps most of the precious CO2 at home. The air movement/ exchange was a real time consuming affair. It took over a week to dial it in because of the quantity of fans, amount of air & heat I deal with, the CO2 issues and ability to actually be in the room when the CO2 is on, to adjust. Man, I got really dizzy fast once the CO2 entered the +800PPM area...
Thanks again...