Will be interesting to see how you get on with those exhale bags i stopped running CO2 during covid and defo noticed a drop in growth/yield but i also got broad mites not long after so that fucked my grow up pretty bad
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CO2-Is it worth it?
- Thread starter sublingual
- Start date
greyfader
Well-known member
if you run sealed rooms you must supplement co2. in rooms that are not sealed you really don't need it if you have enough airflow to keep the co2 level at ambient levels no matter the plant demand, light intensity, or nutrient strength.
co2 is consumed by the plant on a per-unit basis. you cannot make the plant take in more co2 than it needs to match other metabolic processes.
if you pack a bunch of plants or create a large, dense canopy in an unsealed space that does not get enough airflow you will limit metabolism.
i have run a bunch of giant plants in tight spaces with 1500 ppfd of light and ec2.4-2.5 and gotten excellent yields without co2 but with a huge air turnover ratio. like one or two volumes per minute. no problems at all.
just look at plants being grown outdoors at ambient co2 levels producing huge amounts of large flowers.
you don't run co2 in an unsealed space as it is wasted.
on amazon you can find inexpensive co2 monitors for less than 30 US dollars that will tell you if you are getting enough co2 in an open space. if you see the levels drop below ambient you need more airflow.
the plant below was grown without co2 supplementation but with a massive air turnover rate.
the room was only 6 ft wide and 16 ft long with 10 1k lights and 9 plants in all stages of flower. vertical bulbs with cool tubes. the cool tubes were open at the bottom and exhausted the room via ducting and a 400 cfm duct fan on each light.
421 ppm is the average ambient co2 level on the planet right now.
taken from; www.google.com/search?q=world+wide+ambient+co2+level&rlz=1C1VDKB_enUS961US961&oq=world+wide+ambient+co2+level&aqs=chrome..69i57j33i160.638242943j0j15&sourceid=chrome&ie=UTF-8
The current global average concentration of CO2 in the atmosphere is (0.04%) 421 ppm as of May 2022. This is an increase of 50% since the start of the Industrial Revolution, up from 280 ppm during the 10,000 years prior to the mid-18th century.
co2 is consumed by the plant on a per-unit basis. you cannot make the plant take in more co2 than it needs to match other metabolic processes.
if you pack a bunch of plants or create a large, dense canopy in an unsealed space that does not get enough airflow you will limit metabolism.
i have run a bunch of giant plants in tight spaces with 1500 ppfd of light and ec2.4-2.5 and gotten excellent yields without co2 but with a huge air turnover ratio. like one or two volumes per minute. no problems at all.
just look at plants being grown outdoors at ambient co2 levels producing huge amounts of large flowers.
you don't run co2 in an unsealed space as it is wasted.
on amazon you can find inexpensive co2 monitors for less than 30 US dollars that will tell you if you are getting enough co2 in an open space. if you see the levels drop below ambient you need more airflow.
the plant below was grown without co2 supplementation but with a massive air turnover rate.
the room was only 6 ft wide and 16 ft long with 10 1k lights and 9 plants in all stages of flower. vertical bulbs with cool tubes. the cool tubes were open at the bottom and exhausted the room via ducting and a 400 cfm duct fan on each light.
421 ppm is the average ambient co2 level on the planet right now.
taken from; www.google.com/search?q=world+wide+ambient+co2+level&rlz=1C1VDKB_enUS961US961&oq=world+wide+ambient+co2+level&aqs=chrome..69i57j33i160.638242943j0j15&sourceid=chrome&ie=UTF-8
The current global average concentration of CO2 in the atmosphere is (0.04%) 421 ppm as of May 2022. This is an increase of 50% since the start of the Industrial Revolution, up from 280 ppm during the 10,000 years prior to the mid-18th century.
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sublingual
Well-known member
Thank you girls and guys for your insights, and would only disagree maybe on minor things.
I'm growing in a basement open to living space with two adults and pets producing some CO2 which is heavier and sinks. So, ideally, this should benefit my plants. This does not seem to be enough. I run unsealed tents with only the exhaust filtered. The bag just seemed to work. Maybe I just want it to work, but no, I think it's benefitting all the plants. That is why I say, time will tell. I'll keep updating my impressions.
Also, the leaf damage is variable from plant to plant. That big Sativa is a Haze Malawi cross which is known to be nute sensitive. I have other plants I hand water with the same solution and they are loving it and may want more feed.
I'm growing in a basement open to living space with two adults and pets producing some CO2 which is heavier and sinks. So, ideally, this should benefit my plants. This does not seem to be enough. I run unsealed tents with only the exhaust filtered. The bag just seemed to work. Maybe I just want it to work, but no, I think it's benefitting all the plants. That is why I say, time will tell. I'll keep updating my impressions.
Also, the leaf damage is variable from plant to plant. That big Sativa is a Haze Malawi cross which is known to be nute sensitive. I have other plants I hand water with the same solution and they are loving it and may want more feed.
Hiddenjems
Well-known member
Using those bags isn’t using co2. You need a sealed room a tank or a burner, and a controller. The co2 must stay steady through the daylight hours for the plants to use it effectively. You also want warmer temps.
To make use of light in the 60+ Dli range you need co2 or it’s wasted light.
30% isn’t yield increase isn’t all you’re chasing. They usually finish almost a week faster too.
If you’re making a living growing it’s taking your 100k a year setup and making it 130k.
To make use of light in the 60+ Dli range you need co2 or it’s wasted light.
30% isn’t yield increase isn’t all you’re chasing. They usually finish almost a week faster too.
If you’re making a living growing it’s taking your 100k a year setup and making it 130k.
greyfader
Well-known member
"To make use of light in the 60+ Dli range you need co2 or it’s wasted light."
the plant above was grown at 1500 umols for 12 hours which is a dli of 64.8 moles.
it was grown without co2 supplementation but with massive airflow.
plants outdoors get huge with ambient co2 levels.
the plant above was grown at 1500 umols for 12 hours which is a dli of 64.8 moles.
it was grown without co2 supplementation but with massive airflow.
plants outdoors get huge with ambient co2 levels.
@greyfader
This is how I think about CO2 absorption also. If you measure CO2 within your grow and it is the same as outside your grow (ambient) you likely have as much CO2 available as the plants can use, otherwise CO2 would be lower/depleted in the grow space.
I would be interested in seeing a side by side because I still feel as though at high PPFD you will be limited by atmospheric. Cognitive dissonance at my end.
This is how I think about CO2 absorption also. If you measure CO2 within your grow and it is the same as outside your grow (ambient) you likely have as much CO2 available as the plants can use, otherwise CO2 would be lower/depleted in the grow space.
I would be interested in seeing a side by side because I still feel as though at high PPFD you will be limited by atmospheric. Cognitive dissonance at my end.
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I think it can handle it, but would likely yield more with higher CO2. Not saying you can’t get huge yields without CO2, but in the same conditions yields would be greater with it. In my prior post I wrote about wanting to see a side by side, but thinking again about that, there are plenty of lab “side by sides” already.
Astro1
Active member
People need to stop taking CO2 studies out of context and regurgitating that which they don't fully understand or simply choosing to ignore the niceties to stave off disillusionment.
CO2 studies and examples are derived from controls without space constraints for growth. When people quote 30% (many studies show significantly less) increase they are not talking about plants stuffed into a 4x4 tent where the cardinal limiting factor for yield is determined by exposed canopy surface area. CO2 increases photosynthesis and therefore growth rate...it doesn't increase fruit mass directly where space is the limiting factor at least nowhere near the level people pretend it does. Thats simply a common myth. A guess would be 5-10% at best here.
The benefits of CO2 are faster growth rate
Greater Heat Tolerance (that in itself can make a less than ideal grower yield more)
Again MOST if not all studies (I've yet to see a peer reviewed paper that isn't) are quoting biomass increase due to increased size of the plant as a result of faster growth vs the control resulting in a larger plant at harvest which naturally will have more fruit. They are not talking about plants stuffed edge to edge into a 4x4 tent where you run up against space constraints of whats exposed to light.
Just because people repeat something 1000s of times doesn't make it true.
If you told me that the faster growth rate allows you to cut down on veg time to get the plant large enough to flower and thus allowing you to pull off an extra harvest per year...then I'd be inclined to believe you. But if you're suggesting that given equally sized plants fully grown into a 4x4 tent one will yield 30% more with enrichment vs the other you're going to have to find me a study where that is the case and not some anecdote from personal experience and confirmation bias which so commonly prevails in the grower community.
Having run CO2 in a sealed room (several actually) I can tell you from personal experience they do grow faster, they can take more heat and are certainly less prone to stress (to a point) but I didn't see any significant increase in total yield. In my case I found CO2 enrichment not worth it as I was always limited by exposed flower canopy area not pre flower vegetative growth. I found I could always produce enough cannopy area with a few extra plants in my veg room to always have enough to fully fill the rooms edge to edge for flower and as stated earlier found that adding an extra light and expanding the grow are significantly easier than dealing with CO2.
Take this example....
10x10 canopy is 100 square feet. Expand that area to 11.5x11.5 by adding 9in on all sides and you get 32% more surface area and given correct light coverage 32% more yield for sure not maybe.
Dropping an extra light is easy and short of the bulb/led whatever you're using near permanent. The cost of filling the CO2 alone more than pays for the extra light (maybe a few lights) then add the cost of additional CO2 gear and more complicated near sealed airflow restricted room (unless you want to suck out the majority of the CO2 you're adding and do your part for global warming) the costs simply don't add up with the benefits.
I'm all about simplification and spending the least to get the most...naturally lazy I guess but the above mentality has changed my life, paid fully for my California home, both cars to where I no longer flower indoors. (Just keep my moms for cuttings).
K.I.S.S. This is the way.
CO2 studies and examples are derived from controls without space constraints for growth. When people quote 30% (many studies show significantly less) increase they are not talking about plants stuffed into a 4x4 tent where the cardinal limiting factor for yield is determined by exposed canopy surface area. CO2 increases photosynthesis and therefore growth rate...it doesn't increase fruit mass directly where space is the limiting factor at least nowhere near the level people pretend it does. Thats simply a common myth. A guess would be 5-10% at best here.
The benefits of CO2 are faster growth rate
Greater Heat Tolerance (that in itself can make a less than ideal grower yield more)
Again MOST if not all studies (I've yet to see a peer reviewed paper that isn't) are quoting biomass increase due to increased size of the plant as a result of faster growth vs the control resulting in a larger plant at harvest which naturally will have more fruit. They are not talking about plants stuffed edge to edge into a 4x4 tent where you run up against space constraints of whats exposed to light.
Just because people repeat something 1000s of times doesn't make it true.
If you told me that the faster growth rate allows you to cut down on veg time to get the plant large enough to flower and thus allowing you to pull off an extra harvest per year...then I'd be inclined to believe you. But if you're suggesting that given equally sized plants fully grown into a 4x4 tent one will yield 30% more with enrichment vs the other you're going to have to find me a study where that is the case and not some anecdote from personal experience and confirmation bias which so commonly prevails in the grower community.
Having run CO2 in a sealed room (several actually) I can tell you from personal experience they do grow faster, they can take more heat and are certainly less prone to stress (to a point) but I didn't see any significant increase in total yield. In my case I found CO2 enrichment not worth it as I was always limited by exposed flower canopy area not pre flower vegetative growth. I found I could always produce enough cannopy area with a few extra plants in my veg room to always have enough to fully fill the rooms edge to edge for flower and as stated earlier found that adding an extra light and expanding the grow are significantly easier than dealing with CO2.
Take this example....
10x10 canopy is 100 square feet. Expand that area to 11.5x11.5 by adding 9in on all sides and you get 32% more surface area and given correct light coverage 32% more yield for sure not maybe.
Dropping an extra light is easy and short of the bulb/led whatever you're using near permanent. The cost of filling the CO2 alone more than pays for the extra light (maybe a few lights) then add the cost of additional CO2 gear and more complicated near sealed airflow restricted room (unless you want to suck out the majority of the CO2 you're adding and do your part for global warming) the costs simply don't add up with the benefits.
I'm all about simplification and spending the least to get the most...naturally lazy I guess but the above mentality has changed my life, paid fully for my California home, both cars to where I no longer flower indoors. (Just keep my moms for cuttings).
K.I.S.S. This is the way.
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Hiddenjems
Well-known member
I seriously am shocked by how many of the guys i align with and respect on here that dont supplement co2. Guys with detailed lighting and feed knowledge, really great growers, who will fight this. Its so night and day. Its so evident and simple. Massive greenhouses that hold many agricultural crops REQUIRE co2 supplementation simply because they will mine the air to the point of suffocation without it. Co2 is one of the most important inputs in the plant world, some plants more than others, few that pay you back like in cannabis. 20-30% increases in yield!? On a crop worth a lot?! This is measurable photosynthetic rate increases that transfer to serious yield increases. Ive heard the argument that co2 is bad for the environment and we shouldnt be adding any….but….were adding it to a room full of plants that are quickly converting it to oxygen. Were not the problem there. Do commercial co2 enriched rooms really contribute to global warming issues? I have a hard time with that. In my mind, its essential, 1200ppm is the saturation point before the bang for buck slopes off. Its proven beneficial from clone to flower but is imperative above 600-700umol, otherwise the light is basically a waste. Anyone who says “oh but my garden is stoked at 1200umol and they are healthy etc”, ok, great, change nothing else and supplement to 1200ppm. The results will speak for themselves.
greyfader
Well-known member
i agree with most of what you say here, but i think the 600-700 umol point is a rather low light level to say that light above that point is "wasted" without co2. i know that i have seen gains in flower mass using light up to 1200 ppfd without co2 supplementation but with a high air turnover rate.
but i also know that i get even larger gains with co2 supplementation.
in 28 years i have run both with and without extensively for long periods of time and observed the results.
weighed the results too.
the only times i have run without co2 was when i was in a situation where i could not seal a room because the structure leaked so badly that i couldn't control it.
i greatly prefer co2 and my new room that i am building right now will have co2 supplementation.
i don't think agricultural co2 use harms the environment when using sealed rooms.
Ca++
Well-known member
Perhaps they REQUIRE better air movement. Their is a whole world of 400ppm+ air out there. Which is more than they evolved with. Recent studies of light vs yield have not graphed out as curves, but straight lines.
Venting a 1200ppm room is surely blowing co2 outside. I'm not sure how else you can read that.
That is pretty much where this stops for me. If you can get co2 in a bottle, then keeping it there is the best thing to do with it. People are doing perfectly good grows without co2, and adding it may just grow more... mold. Many co2 users are just using it to keep up with the better growers, or as treatment for a symptom, where they can't find the cause. The better growers are often not using it. They are not blind to it. It just didn't prove useful.
In all honesty, I'm doing around 650g per meter, after loosing near 90% to drying and curing. I'm up against a wall, where any further increase in bud size, just means they mold. So I'm on screens, growing lots of smaller buds, not the big photogenic one's. I know there are fungicides good enough for even pgr buds, but it's just not what I grow. We know a lot of people do have bottles of stuff they won't admit to though. I do have a couple more angles I could explore, such as lower RH, but what sort of fan can blow into the core of a bud. The use of such kit wouldn't be economically viable. It's another light.
As others have said, I will grow more plants if I need more green. It's carbon capture too. If my power company are truly green. This is how I will get into heaven lol
Ca++
Well-known member
It would be on the very low side, for sure. In theory the plant weight expected, should correlate with co2 canister weight. It's maths I have not even thought about before, but the amount of co2 canisters used, would give a good idea of how well sealed a room really was.
In some crazy world, all co2 released should go to the plants. You could then let it drop to 400ppm before venting through the night. You could claim more co2 is captured in your plant waste, than goes out your exhaust.
It doesn't have to be bad. However the handling of many installations, often run by people that didn't even need it, makes advertising it's uses something I avoid. Global co2 needs reducing, so I'm never going to suggest someone uses it. Maybe on some other forum somewhere... but not on a hobbiest forum, the public can readily access.
CharlesU Farley
Well-known member
I _really_ understand the drive for efficiency and optimization when cultivating cannabis. But at what point do you get an actual ROI for all the time, effort, measurements, etc., not to mention cost, that is done with all of this so-called "optimization"? Just to achieve maybe a 5 to 10% increase in bud size/yield but not in actual cannabinoid content?
Because bud mass / weight is increased but actual cannabinoid content is not. Light, what y'all call DLI, has absolutely no effect on cannabinoid content... whatsoever.
When you're developing (oh my God I can't believe I'm going to use this fucking term but there's probably some Millennials that may be reading this, so I have to use terms they'll understand) "craft cannabis", what massive greenhouses that generate thousands of plants with absolutely no human intervention do is absolutely no importance.
It's the quality, not the quantity.
greyfader
Well-known member
hey, chuck! "Because bud mass / weight is increased but actual cannabinoid content is not. Light, what y'all call DLI, has absolutely no effect on cannabinoid content... whatsoever."
just for consideration, how do you then explain the stratification of cannabinoids on a plant relative to distance from the light?
Rocket Soul
Well-known member
We have high CO2 levels naturally in our grow, thru the use of gasheaters in some areas and the living areas being heated by wood fire in winter so hard to say what wed get without it. Infact sometimes we worry about too much, it easily gets up to 1500 just thru notmal life in the house.
Weve seen some situations were CO2 wasnt beneficial in our veg area and after research it looks like it could have to do with lower transpiration: CO2 tends to close the stomata in horticulture research. Im surprised nobody brought it up in this thread but it could also be why there are so much difference in opinions on if it works or is worth it. Somebody stated photosynthesis is light + CO2, this is not completely correct, its actually light + C02 + water and actual plant growth also require nutes. Better yet photosynthesis is CO2+light+transpiration.
With leds already being a bit harder to make plants transpire its probably best to state what light you were using when stating your personal experience/opinion on CO2.
Weve seen some situations were CO2 wasnt beneficial in our veg area and after research it looks like it could have to do with lower transpiration: CO2 tends to close the stomata in horticulture research. Im surprised nobody brought it up in this thread but it could also be why there are so much difference in opinions on if it works or is worth it. Somebody stated photosynthesis is light + CO2, this is not completely correct, its actually light + C02 + water and actual plant growth also require nutes. Better yet photosynthesis is CO2+light+transpiration.
With leds already being a bit harder to make plants transpire its probably best to state what light you were using when stating your personal experience/opinion on CO2.
CharlesU Farley
Well-known member
Apical dominance.
Ca++
Well-known member
Interestingly, Apical doesn't fit. It's a term applied through observation, when under just a top light. Most of the surrounding explanation fits, except the idea it's a top down thing. This was shown quite well in my thread where I put lights on the floor. The lower buds where nice, but the middle ones were fodder.
I do see what you are pointing at. For example, a longer day produces more weight, yet very little extra cannibinoids. Giving a dilution effect, well beyond any usefulness as a craft grower. I think this is why many co2 users stop mid bloom. It reduces bulking, but the plant and it's roots are capable. However, this is ignoring the idea light makes the sugars, that get to the roots, which seem to be important to cannibinoid production. This is all very dated thinking now though. I'm just parroting old ideas, that are not my own.
I do like to bring on cuts and seeds in a co2 rich environment. Seeds are perhaps more likely to benefit. As their early expression is surely set in them very early hours/days. I had a friend try to wake them with coffee once. It's that important lol
CharlesU Farley
Well-known member
We'll have to agree to disagree on that.
Impact of Different Phytohormones on Morphology, Yield and Cannabinoid Content of Cannabis sativa L.
"Above all, the inflorescence yields are decisive, since a higher content of cannabinoids is expected. Stout et al. [46] reported the highest CBD levels in Cannabis flowers, with lower amounts in leaves. Cannabinoids can be extracted from the reproductive plant parts and foliage. Inflorescence has higher concentrations of cannabinoids than foliage material, however foliage parts comprise the lager biomass of the Cannabis plant [47]. The PCR genetics used in the present study showed lower leaf DW compared to inflorescence DW. Leaf DW yield depended on the genotype and treatment, where genotype KANADA showed the highest DW leaf yields and genotypes 0.2x and FED were not that profitable. The use of PGR did not reduce leaf yield for BAP-treated and NAA/BAP-mix-treated plants."
