When to Stop co2 Increase During Flowering?

linky

Well-Known Member
35-45 rh is way to low, especially if you are going by vpd chart, with mid to high 80's leaf temp you should be at ~75% humidity.
 

DirtyEyeball696

Well-Known Member
Ok got a question what is a good temp to maintain 45-50% humidity consistently
I'm noticing when the lights go off it seems to rise. I have my temp set at 73 when they go off. Should I raise it to 75 maybe?


Kush Is My Cologne
 

DirtyEyeball696

Well-Known Member
I have 2 Aprilaire 90 pint a day. Everything seems ok until the lights go off and it seems to raise so I was wondering if I raised my "lights off" temp it might make my dehumidifiers. Maybe 75 degrees.


Kush Is My Cologne
 

Rasta Roy

Well-Known Member
I have 2 Aprilaire 90 pint a day. Everything seems ok until the lights go off and it seems to raise so I was wondering if I raised my "lights off" temp it might make my dehumidifiers. Maybe 75 degrees.


Kush Is My Cologne
Exhaust that air out of your room when your lights click off fam!
 

Rasta Roy

Well-Known Member
PLENTY of scientific PAPERS available on the web to read on exactly this subject and it's parts described here!

Start looking!
You're the man for that post. Co2 use (like everything in the cannabis community) is full of misinformation even though there's good information out there.
 

DirtyEyeball696

Well-Known Member
Exhaust that air out of your room when your lights click off fam!
Still kinda confused on the temperature to run when the lights are off so the dehumidifiers stay on properly. Like I said when the lights go off and temps drop I have my thermostat set to 73, should I go maybe 75 to ensure proper dehumidification? I have whole home dehumidifiers not small single ones. They are set up a little differently 90-95 pints a day X 2 is ample for my 20 x 20. Just kinda confused not on the co2 part cause I have an automatic controller but more on nighttime temps to keep RH 45-50
If I'm in the wrong forum let me know
Thanks


Kush Is My Cologne
 

organixx325

Active Member
I use humidity controllers to control humidifiers/dehumidifiers. Set it to to whatever humditity you want it to kick on and have it exhaust out when it reaches the set humidity.
 
Even at night I use 72 deg F, and keep the dehums' going.

I like to keep things cool - The AC's dry the air so well, I like to keep them working hard to increase VPD. Are your dehumidifiers able to keep up ?

CO2 will get into the plant easily if the plant has no water stress, so I keep roots wet and I don't let air get warmer than 78 Deg F.

I'd set the AC's to run at 72 deg F, expecting leaf temps to be 77 deg or so in the day. If your dehum's discharge heat into the grow room, that will also trigger the ACs to run more, and together they'll just wring the water out of the air!

With a big crop I like to see the %RH of the air around 45-50% after irrigating, and I let it go as low as 30-35% before watering, but the soil is always wet. I usually water when the soil has dried to 70% of saturated (measured by the weight of a freshly watered pot= 100%). If roots run out of easy-to-absorb water, growth slows or stops; keep the soil wet !

With dry air and wet roots, plants transpire more, which equals faster and bigger growth. I usually set dehumidifiers to run until 40-45%RH. If you capture the AC and dehum' condensate, it's not unusual to irrigate with 1000 liters one day, and have almost 1000 liters returned to the reservoir within 24-36 hours.

It's true that the enzyme RUBISCO operates faster at warmer temperatures, but letting air temp rise to promote stomatal opening for cooling the plant often increases the air's humidity (lowers VPD). To enable the best use of CO2 we just want to keep the stomata wide open, so avoid any drought or water stress.

In contrast to RUBISCO's preference for warmer temps while it captures CO2 and makes carbohydrates, the photochemistry part of photosynthesis where chlorophyll is catching photons actually runs better at cooler temperatures. The green photosynthetic membranes in chloroplasts will overheat in high light and are constantly trying to dissipate that heat, so I like to keep air temp on the cool side. 70 - 72 deg. F, and keep the CO2 levels between 600 to 1200 ppm.
 

DirtyEyeball696

Well-Known Member
Even at night I use 72 deg F, and keep the dehums' going.

I like to keep things cool - The AC's dry the air so well, I like to keep them working hard to increase VPD. Are your dehumidifiers able to keep up ?

CO2 will get into the plant easily if the plant has no water stress, so I keep roots wet and I don't let air get warmer than 78 Deg F.

I'd set the AC's to run at 72 deg F, expecting leaf temps to be 77 deg or so in the day. If your dehum's discharge heat into the grow room, that will also trigger the ACs to run more, and together they'll just wring the water out of the air!

With a big crop I like to see the %RH of the air around 45-50% after irrigating, and I let it go as low as 30-35% before watering, but the soil is always wet. I usually water when the soil has dried to 70% of saturated (measured by the weight of a freshly watered pot= 100%). If roots run out of easy-to-absorb water, growth slows or stops; keep the soil wet !

With dry air and wet roots, plants transpire more, which equals faster and bigger growth. I usually set dehumidifiers to run until 40-45%RH. If you capture the AC and dehum' condensate, it's not unusual to irrigate with 1000 liters one day, and have almost 1000 liters returned to the reservoir within 24-36 hours.

It's true that the enzyme RUBISCO operates faster at warmer temperatures, but letting air temp rise to promote stomatal opening for cooling the plant often increases the air's humidity (lowers VPD). To enable the best use of CO2 we just want to keep the stomata wide open, so avoid any drought or water stress.

In contrast to RUBISCO's preference for warmer temps while it captures CO2 and makes carbohydrates, the photochemistry part of photosynthesis where chlorophyll is catching photons actually runs better at cooler temperatures. The green photosynthetic membranes in chloroplasts will overheat in high light and are constantly trying to dissipate that heat, so I like to keep air temp on the cool side. 70 - 72 deg. F, and keep the CO2 levels between 600 to 1200 ppm.
Ok thanks


Kush Is My Cologne
 

vilify

Well-Known Member
my best results came from starting around 1800 ppm the first two weeks and lowering 200-300 every week.
 
If you have enough light to drive the 'extra' photosynthesis, always enrich with CO2, right to the end.

Just a few facts about plant physiology to consider:

All green parts of the plant, every green cell there is, are trying to fix CO2, and capture it and build the CH2O carbohydrate into the 'body' of the plant. Even green buds, stems and calyxes fix CO2 into CH2O's. The whole green plant is starving for CO2.

Remember - 45% of the dry weight of a bud is made of carbon, and it all came from CO2 in the air! That's almost half of the dry weigh of our crops is carbon alone, so CO2 enrichment works; it will increase yield if you have high enough light levels.

The leaf temperature is always warmer than the air tempearture. 85 deg F in the air is 90-92 deg F on the leaves... To increase VPD, which makes plants transpire more, just cool to 70 Deg F with air conditioners. A 70 Deg air temperature is a 75 deg F leaf temp.

Cooling the air with AC's dries the air alot, so AC's pull the water out of the plants, the operating AC's are 'growing' the plants too!. Transpiration equals growth; the plant that uses 10 liters of water a day is growing bigger than the plant using just 2 liters a day. With unlimited water in the root zone, stomata are open, and CO2 pours into the plant.

Also plants always acclimate to a high level of CO2, they get 'lazy' and make way less RUBISCO enzymes if exposed to high CO2 levels all the time. This enzyme is the one that 'grabs' CO2 from the air; plants won't invest in making more RUBISCO if the CO2 level is high. This has been studied in detail, as RUBISCO is the most abundant enzyme on Earth; it enables all life!

Inside plant cells there are way more RUBISCO enzymes to take a 'gulp' of CO2 from the air if CO2 is running at 500ppm, than when plants have been growing at 1500 ppm CO2. These enzymes cost the plant to make, and their turn-over rate is fast, they aren't synthesized in the dark, and will even be broken down at night. In the day time plants make as much RUBISCO as they 'think' they need.

So if you vary CO2 levels between a low of 600 ppm and a high of 1200 ppm, more CO2 will be 'eaten' from the air by the plants as they will not get 'lazy' by synthesizing less RUBISCO enzymes. Turn on CO2 injection at 600 ppm, turn it off at 1200 ppm, and then let the crop suck the CO2 back down to 600 ppm before injecting more.

The fastest growth by plants happens when they have unlimited water at their roots, and when the VPD is highest (ie 35-45% RH), combined with high light levels (ie PFD or photon flux density) at 1500-1800 umol (like the sun!), and they have dynamically enriched CO2 levels.

Combine this with ideal air temperature (75 Deg F) and balanced mineral nutrients, and the plants transpire like crazy, fix CO2 like mad as light drives the 'engine' of photosynthesis at full speed, and you get maximum yield.
Would you suggest exhausting
If you have enough light to drive the 'extra' photosynthesis, always enrich with CO2, right to the end.

Just a few facts about plant physiology to consider:

All green parts of the plant, every green cell there is, are trying to fix CO2, and capture it and build the CH2O carbohydrate into the 'body' of the plant. Even green buds, stems and calyxes fix CO2 into CH2O's. The whole green plant is starving for CO2.

Remember - 45% of the dry weight of a bud is made of carbon, and it all came from CO2 in the air! That's almost half of the dry weigh of our crops is carbon alone, so CO2 enrichment works; it will increase yield if you have high enough light levels.

The leaf temperature is always warmer than the air tempearture. 85 deg F in the air is 90-92 deg F on the leaves... To increase VPD, which makes plants transpire more, just cool to 70 Deg F with air conditioners. A 70 Deg air temperature is a 75 deg F leaf temp.

Cooling the air with AC's dries the air alot, so AC's pull the water out of the plants, the operating AC's are 'growing' the plants too!. Transpiration equals growth; the plant that uses 10 liters of water a day is growing bigger than the plant using just 2 liters a day. With unlimited water in the root zone, stomata are open, and CO2 pours into the plant.

Also plants always acclimate to a high level of CO2, they get 'lazy' and make way less RUBISCO enzymes if exposed to high CO2 levels all the time. This enzyme is the one that 'grabs' CO2 from the air; plants won't invest in making more RUBISCO if the CO2 level is high. This has been studied in detail, as RUBISCO is the most abundant enzyme on Earth; it enables all life!

Inside plant cells there are way more RUBISCO enzymes to take a 'gulp' of CO2 from the air if CO2 is running at 500ppm, than when plants have been growing at 1500 ppm CO2. These enzymes cost the plant to make, and their turn-over rate is fast, they aren't synthesized in the dark, and will even be broken down at night. In the day time plants make as much RUBISCO as they 'think' they need.

So if you vary CO2 levels between a low of 600 ppm and a high of 1200 ppm, more CO2 will be 'eaten' from the air by the plants as they will not get 'lazy' by synthesizing less RUBISCO enzymes. Turn on CO2 injection at 600 ppm, turn it off at 1200 ppm, and then let the crop suck the CO2 back down to 600 ppm before injecting more.

The fastest growth by plants happens when they have unlimited water at their roots, and when the VPD is highest (ie 35-45% RH), combined with high light levels (ie PFD or photon flux density) at 1500-1800 umol (like the sun!), and they have dynamically enriched CO2 levels.

Combine this with ideal air temperature (75 Deg F) and balanced mineral nutrients, and the plants transpire like crazy, fix CO2 like mad as light drives the 'engine' of photosynthesis at full speed, and you get maximum yield.
What's your thoughts on co2 inhibiting ethylene production late flower, atmospheric levels during ripening phase?
 

guitarzan

Well-Known Member
I just bought an ExHale Co2 bag...I have two plants that are near ready, already Final Flushed them and plain pHed water...I was planning on leaving the bag hanging until they're finished...kinda on the fence with thiis though.
 

Renfro

Well-Known Member
I just bought an ExHale Co2 bag...I have two plants that are near ready, already Final Flushed them and plain pHed water...I was planning on leaving the bag hanging until they're finished...kinda on the fence with thiis though.
Well lemme guess, you are using a blower to ventilate your space for cooling purposes? If so, the CO2 is exhausted faster than it's produced.
 

Terpenefiend

New Member
That high of humidity is causing me anxiety and my monitor and controller won’t even be here until tomorrow. I am now contemplating just send the fuckers back. What’s the point of an increased yield if the chances of losing it to bud rot is that high?
 

AlexQc

Member
35-45 rh is way to low, especially if you are going by vpd chart, with mid to high 80's leaf temp you should be at ~75% humidity.
ambiant humidity at 40-50% will reach easily 60-70% humidity when burst of transpiration of the plant occur you both are right but doesn't calculate the same humidity factor ...
 

TeW33zy

Active Member
The reason for this is limiting factors. Co2/oxygen/light/nutrients/temp must essentially be balanced. If given numbers just for the sake of explaining, let's say you run all factors at '2', but then decide to increase co2 to '3'. To simplify the explanation the plants will still grow at '2' or only slightly faster unless you increase everything. Ed Rosenthal explains it in his book I believe ;)
WHAT? No no no. The reason you don't run co2 during the last 2 weeks is because of the Ethylene the plant produces to ripen your flowers. Ethylene is a hydrocarbon gas that plants produce at the end of there life cycle to ripen. If you run high levels of co2 while the plant produces Ethylene c2H4 it effects the hydrocarbon compounds. Ethylene has 2 carbon atoms and 4 hydrogen atoms which work together to ripen. This process is undergoing 4 types of reactions - oxidation, polymerization, halogenation, and hydration which is how you buds get that ripen look and oils.

You never want to affect the Ethylene ripening process, literally 2 gases in high concentrations effect each other. Co2 goes up, Ethylene stays down, Ethylene goes up, Co2 goes down, never ever up at the same time. No different than you guys putting a boveda 62% humidity pack in the jar during the sweating process, u never ever do that. You burp the jar until the jar consistently stays at 56-60% then after its stable a few days later u add the boveda pack so it's not affecting the sweating process. If you run extra co2 while the plant is producing Ethylene c2h4 your plant will literally not ripen correctly and you will have decreased quality, decreased oils, terpenes and everything. Don't do it.

I hope this helps.

~ Sr. Quality Engineer, M.S, (Medical)
 
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calvin.m16

Well-Known Member
co2 enrichment only needs to be stopped when lights are off. I've noticed no benefit to turning off co2 late bloom.. If your co2 was to shut off the best time would be late bloom though, any other time the plants will be consuming much more of it. When I first flip plants into 12/12 my co2 burner runs a lot more than usual for the first few weeks during stretch, then it kinda slows down and isn't kicking on as much. Late bloom it only runs a few times here n there.. That is how I know at least.. Basic observation over the last couple years of using co2.

p.s don't run co2 higher than 1500 PPM anything higher and your starting to actually cause plants to reduce transpiration and close their stomata due to being enriched with co2 heavily. Keep your co2 ideally in the 1000-1200 range for the best results. I see some new to co2 people running it at insane levels like 2000-2,200, at those levels it can actually have an adverse effect.
 
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Samwell Seed Well

Well-Known Member
so when CO2 intake wears down I take it that means the photosynthesis rate slows down, too. which would warrant to reduce light influx, isnt it?
Funny how the plant tells you.. as its finishing its cycle

Eats less, transpires less...
To OP
Plants do all the work, just pay attention and open and close the right doors
 
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