# Co2 and vpd?



## mhalter81 (Nov 18, 2020)

Been growing for about two years now. Just started co2 recently, I understand that my temps need to be 82 to 85ish to take the most advantage of co2 enrichment. Is that room temps or canopy temps? Currently running 79 degrees in room humidity around 58 percent, canopy at 84-85 humidity much lower of course. According to the pulse vpd chart im good for room vpd and very poor considering canopy. Plants are looking very healthy, but im afraid im missing out on potential, or wasting CO2. Can someone please help?


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## BobThe420Builder (Nov 18, 2020)

Never used c02, never an issues

Sealed room they say can benefit, but I see no need for it


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## mhalter81 (Nov 18, 2020)

Gotcha. No issues here either, other than am I wasting CO2. I do have a sealed room. Just keep reading about growth potential with co2, I live in a state with plant restrictions, so if I can get 10 to 20% more product with same resources, why not?


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## BobThe420Builder (Nov 18, 2020)

I'd say work on your grow knowledge and process to increase production


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## Fernvalley (Nov 18, 2020)

I run my canopy at around 83-84 and humidity between 50-60. If you're locked in at growing without supplemental co2, you'll see a big benefit to growth rate and yield.

When I started using co2, I increased my yields by 60%...BUT HOLD ON. I was growing is a sealed room with a ton of biomass growing. I picked up a co2 controller before I got a tank and placed it in the room. I noticed that each day I was dropping below 250ppm at many points. So really I was correcting a problem that I didn't know I had.

But I will never grow without it again.


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## BobThe420Builder (Nov 18, 2020)

Fernvalley said:


> I run my canopy at around 83-84 and humidity between 50-60. If you're locked in at growing without supplemental co2, you'll see a big benefit to growth rate and yield.
> 
> When I started using co2, I increased my yields by 60%...BUT HOLD ON. I was growing is a sealed room with a ton of biomass growing. I picked up a co2 controller before I got a tank and placed it in the room. I noticed that each day I was dropping below 250ppm at many points. So really I was correcting a problem that I didn't know I had.
> 
> But I will never grow without it again.



Pretty hard to believe unless you really sucked at growing prior to adding c02...lol


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## mhalter81 (Nov 18, 2020)

BobThe420Builder said:


> I'd say work on your grow knowledge and process to increase production


You are correct, everyone should do this. Thats why I asked the question. Without co2 my plants were healthy throughout grow, I would average anywhere from .85 to 1 gram per watt cured. I try to strive for perfection. Again, if I can get more yield, denser buds with CO2 at same cost why not try and achieve that. Btw, I get Co2 for free.


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## Fernvalley (Nov 18, 2020)

BobThe420Builder said:


> Pretty hard to believe unless you really sucked at growing prior to adding c02...lol


Great response. And from someone that has no experience using supplemental co2. 

Not saying I was the best grower on earth...but I had a ton of foliage for the cubic footage of my grow space. The plants were very healthy...just slow growing and modest yield. They consumed the ambient co2 at a high rate causing the levels to bottom out. And at this point they stall. 

Just sharing my personal experience.


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## mhalter81 (Nov 18, 2020)

Fernvalley said:


> I run my canopy at around 83-84 and humidity between 50-60. If you're locked in at growing without supplemental co2, you'll see a big benefit to growth rate and yield.
> 
> When I started using co2, I increased my yields by 60%...BUT HOLD ON. I was growing is a sealed room with a ton of biomass growing. I picked up a co2 controller before I got a tank and placed it in the room. I noticed that each day I was dropping below 250ppm at many points. So really I was correcting a problem that I didn't know I had.
> 
> But I will never grow without it again.


Thanks for your relative input for the question asked above.


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## pahval (Nov 21, 2020)

hey mate, i hope i can help, i just posted about this somewhere else on this forum, ill post my resources again:

[...] well, you have to measure temperature of air around the plants (so in canopy level, it wont help much if you measure temps around your lamp), AND you have to measure your leaves temps, i would suggest handheld IR thermometer for that, because we are measuring difference of air vapor saturation and leaf vapor saturation, and that is the vapor pressure deficit we want to have so that our plants can transpire as much as they can without any stress... a good chart, which takes into account your leaf temp (but it looks ugly), can be found here:



VPD Calculator by Everest Fernandez



a good info about vpd i have found here:






and good info about temps and other with using co2 i have found here:









Factors that influence growth and development ( Temp and VPD)


I’ve uploaded the Fluence guide before, here’s the complete version Fluence Bioengineering_High PPFD Cultivation Guide_v1.2.pdf (1.4 MB) another good one! Lumigrow LumiGrow_LED_Growers_Guide_for_Cannabis.pdf (2.0 MB) and not to be outdone…Illumitex…we got 'em all here at OG...




overgrow.com





especially pdf from fluence, which has recommended temperatures with and without co2 supplementation...


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## mhalter81 (Nov 21, 2020)

pahval said:


> hey mate, i hope i can help, i just posted about this somewhere else on this forum, ill post my resources again:
> 
> [...] well, you have to measure temperature of air around the plants (so in canopy level, it wont help much if you measure temps around your lamp), AND you have to measure your leaves temps, i would suggest handheld IR thermometer for that, because we are measuring difference of air vapor saturation and leaf vapor saturation, and that is the vapor pressure deficit we want to have so that our plants can transpire as much as they can without any stress... a good chart, which takes into account your leaf temp (but it looks ugly), can be found here:
> 
> ...


Thank you so much, the plethora of information that you have given me this day, is very much appreciated. I have quickly skimmed through all of it, and plan on referring back to it over the next several days. Even though I was very unsure of myself attempting what I'd consider next level grow methods, I am within close range of optimal cultivation. I honestly believe this info will help me succeed at the next level. Again, thank you so much!


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## J232 (Nov 21, 2020)

You would want to adjust the air temp to reach a desired leaf temp. I skimmed threw and didn’t see your lighting, that will factor in there too. If you are new to co2, as I am, I would grab a IR thermometer. I have no problems growing without, I didn’t want to exhaust my room outdoors in winter as it would look like a power plant stack in my mind. I can only assume the free co2 is food grade as well.


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## pahval (Nov 21, 2020)

J232 said:


> You would want to adjust the air temp to reach a desired leaf temp. I skimmed threw and didn’t see your lighting, that will factor in there too. If you are new to co2, as I am, I would grab a IR thermometer. I have no problems growing without, I didn’t want to exhaust my room outdoors in winter as it would look like a power plant stack in my mind. I can only assume the free co2 is food grade as well.


yep, thats also a thing, co2 must be food grade... if you go with co2, you need more of lights and nutes... also, if you go with higher VPD that will mean plant will absorb more water, hence will absorb more nutrients, so be careful about it, maybe you just need to raise vpd (make plant intake more), or you keep same vpd as before co2 and enrich your nutrient solution more... anyway, im glad to help out! <3


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## mhalter81 (Nov 21, 2020)

I attached several pics( don't mind the clutter, cleaning up veg room at the moment). Again everything seems to be healthy, two more days will be the beginning of 4th week of flower. The lower temp/ higher rh is room air, the higher temp/ lower rate is at canopy level. My current leaf temp is anywhere from 76 to 79 degrees. I am running 24 hlg 132qb's @ 1400ma12 hrs a day (par is at its highest 1136umole and 697 at the very far corners) and 4 super b uvb bulbs 3.5 hours a day(also something new for me). 4x8 room, plants veg for approx 6 weeks. Vpd is hard for me to wrap my head around, mostly because all of the resources that I own say to keep humidity levels much lower than what vpd charts claim. Anyway, thanks again to everyone that has helped thus far. Before anyone says anything I know I have a lot of wasted space. Lol


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## pahval (Nov 21, 2020)

They look nice... Lower rh recommendation is to prevent having bud mold, but from what ive seen these people also have high temps, mold comes with high temp and hum, ive red somewhere tha user had high temp and hum trough the day and lower (esp. humidity) trough the night and had no problems... And in the end, if it works for you, just follow that, you can experiment on some smaller grow...


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## TintEastwood (Nov 21, 2020)

Good info here...






CO2 Enriched Hydroponic Growing | Manic Botanix – Manic Botanix







manicbotanix.com





The above has helped me become a better grower. Co2 supplemented or not.

I keep room in the 80s. W leds/cmh
Leaf surface temps in the low 80s.
Rh 50 avg. no higher than 60.
That's with Co2, between 600ppm in veg, up to 900 max. in flower.


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## NukaKola (Nov 21, 2020)

mhalter81 said:


> I attached several pics( don't mind the clutter, cleaning up veg room at the moment). Again everything seems to be healthy, two more days will be the beginning of 4th week of flower. The lower temp/ higher rh is room air, the higher temp/ lower rate is at canopy level. My current leaf temp is anywhere from 76 to 79 degrees. I am running 24 hlg 132qb's @ 1400ma12 hrs a day (par is at its highest 1136umole and 697 at the very far corners) and 4 super b uvb bulbs 3.5 hours a day(also something new for me). 4x8 room, plants veg for approx 6 weeks. Vpd is hard for me to wrap my head around, mostly because all of the resources that I own say to keep humidity levels much lower than what vpd charts claim. Anyway, thanks again to everyone that has helped thus far. Before anyone says anything I know I have a lot of wasted space. Lol


Dig the QB 132's! How are you liking the Autopilot APC8200? Was thinking about picking one up.


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## mhalter81 (Nov 22, 2020)

NukaKola said:


> Dig the QB 132's! How are you liking the Autopilot APC8200? Was thinking about picking one up.


Thanks. Autopilot has worked well so far. I dont care for the lights on it, but hasn't seemed to cause any problems yet.


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## insomnia65 (Dec 25, 2020)

pahval said:


> hey mate, i hope i can help, i just posted about this somewhere else on this forum, ill post my resources again:
> 
> [...] well, you have to measure temperature of air around the plants (so in canopy level, it wont help much if you measure temps around your lamp), AND you have to measure your leaves temps, i would suggest handheld IR thermometer for that, because we are measuring difference of air vapor saturation and leaf vapor saturation, and that is the vapor pressure deficit we want to have so that our plants can transpire as much as they can without any stress... a good chart, which takes into account your leaf temp (but it looks ugly), can be found here:
> 
> ...


The guy on that video could do with breathing only CO2 for a a while grr.


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## Renfro (Dec 25, 2020)

Fernvalley said:


> I noticed that each day I was dropping below 250ppm at many points. So really I was correcting a problem that I didn't know I had.


One thing about CO2 enrichment, the plants actually perform better if you have low points and high points. I wish that I could set a larger dead band on my CO2 controller personally but I can use periodic vent cycles on a timer to achieve the same thing.


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## dbz (Dec 25, 2020)

Renfro said:


> One thing about CO2 enrichment, the plants actually perform better if you have low points and high points. I wish that I could set a larger dead band on my CO2 controller personally but I can use periodic vent cycles on a timer to achieve the same thing.


I am adding co2 to my flowering room I am finishing up. You saying get it back down near 400 ppm during lights off...or even some ramping up and down during on?


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## Renfro (Dec 25, 2020)

dbz said:


> I am adding co2 to my flowering room I am finishing up. You saying get it back down near 400 ppm during lights off...or even some ramping up and down during on?


I don't remember the exact science behind it but it had to do with the plants opening up their stomata and really working to get the CO2 during periods of lower PPM, then when you ramp it up they have a period of peak performance before they start to close up the stomata due to the surplus of CO2 available. There was someone that explained it better on here once so I started playing with it. I have found that it seems to benefit if you can have that occur more than just once a day at lights on.


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## mr4tune (Dec 26, 2020)

pahval said:


> yep, thats also a thing, co2 must be food grade... if you go with co2, you need more of lights and nutes... also, if you go with higher VPD that will mean plant will absorb more water, hence will absorb more nutrients, so be careful about it, maybe you just need to raise vpd (make plant intake more), or you keep same vpd as before co2 and enrich your nutrient solution more... anyway, im glad to help out! <3


Someone can correct me if I'm wrong, but there is no need for food grade co2 in your grow room. Industrial co2 is fine, and is half the cost (at least where I get it from). Food grade is for home brewing. No different than if you are using a burner. Propane is propane.

Not related to the above comment, I'm also interested in why so many post say that you need to be running 85F - 90F when using co2. From what I've read, Co2 intake is all about correct VPD. I'll run higher (85f) when in veg just to save on cooling costs, but there are different vpd pressure ranges based on how far along you are. The quality of my meds greatly increased when I started following the correct ranges for each range (veg, late veg/ early flower, late flower) versus trying to follow the same vpd range from start to finish. Just my experience anyways. That's why you need full control of your environment to be able to hit those set points for temp/humidity in flower. You should have the ability to pick a temp and be able to match the humidity with a few clicks. Most guys I see running co2 throw it into a room thats too hot and too dry and then expect a miracle.

Your lighting plays a huge part. I struggled to attain the proper vpd range when I was running HPS or CMH. Soon as I switched to LED panels my temps dropped by 2/3 and its a cake walk now.


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## mhalter81 (Jan 29, 2021)

Well, I did not use "food grade" CO2. Harvested 918g off 4 plants, from seed to harvest 17 full weeks. I'm happy with those numbers, im sure everything 100% perfect, I could have yielded more. My grow will never be 100%, so these numbers are great for me. Thanks to everyone that took the time to respond!!!!


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## ÒÒlegilizeitÒÒ (Jan 30, 2021)

mhalter81 said:


> Well, I did not use "food grade" CO2. Harvested 918g off 4 plants, from seed to harvest 17 full weeks. I'm happy with those numbers, im sure everything 100% perfect, I could have yielded more. My grow will never be 100%, so these numbers are great for me. Thanks to everyone that took the time to respond!!!!


Hey I know its alittle late, but there are a lot of calculators out there that actually require an input of air temp, and leaf temperature, and RH to calculate the offset and spit out the most accurate VPD number.


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## heath2019 (Aug 6, 2022)

mhalter81 said:


> Been growing for about two years now. Just started co2 recently, I understand that my temps need to be 82 to 85ish to take the most advantage of co2 enrichment. Is that room temps or canopy temps? Currently running 79 degrees in room humidity around 58 percent, canopy at 84-85 humidity much lower of course. According to the pulse vpd chart im good for room vpd and very poor considering canopy. Plants are looking very healthy, but im afraid im missing out on potential, or wasting CO2. Can someone please help?


I use co2 bag and use VPD from growdoctor.com. Have the prettiest health plants. Also the website has a calculation for your nutrient mix. Very helpful site and this is my first time growing. DWC and looks to yield about 30 oz. Gonna try this water curing also. Saw that on another website and it makes a lot of sense. Might want to check it out. Good Luck


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