85f / 75f best temp for CO2 ?

[max_well]

I'm trying to get insight about the best conditions to provide for a sealed environment with CO2 supplementation. I've read some differing suggestions for ideal day/night temperature. Does anyone have reference to published literature / studies to confirm the common suggestion of 85f day / 75f night for CO2 enhanced to ~1200-1500ppm ? I can understand why a higher daytime temp might be required to make best use of the enhanced CO2 levels, but why would having higher lights off temps (75 compared to the standard 65f recommendation for open rooms) benefit the plants, as there is no CO2 supplementation during the dark period?? Maybe it's just healthier to avoid too large a differential between day and night?
Any thoughts are appreciated.
thanks
Max

 

[milehighmedical]

Um, just use CO2 during lights on... atleast 80 during the day, up to 86F.

 

[Philosophelon]

Maybe it's just healthier to avoid too large a differential between day and night?

Yup, my guess is that the reason you have been advised to maintain 75deg at night and 85deg during the day is because a large difference between day and night temps can stress your plants. You'll start to see growth tips yellowing and slow growth.

Here is a pic courtesy of MyNameStitch.



Try and keep your night temps within 10-15deg of your day temps. Sensitivity to temperature varies with strain, and Indica-dominant strains will generally tolerate a bigger change than Sativa-dominant strains. Also, if the rooting media temps are too cold (from being placed on a concrete floor, etc.) you can run into temp stress.

 

[Cheeb]

I never have experienced what I'd call stress from temp variances from day/night..just a bit of stretch.

I say optimal temp is 75-80 regardless of whether co2 is being used or not.

Show me a room using co2 at 85-86..then drop those temps to 75-77 and I bet you'll see gains.

just my opinion

 

[max_well]

THanks for the feedback.
I've also read that higher levels of nutrient ppm / light intensity are necessary to take full advantage of CO2 enrichment. I've definitely seen gains with CO2, but haven't had enough runs or resources to play around with the parameters of temp /light /nutrient levels to know if higher tolerances for each are really required to max things out.

I have seen that introducing enhanced CO2 suddenly during mid flowering is NOT a good idea: a super healthy crop started showing all sorts of nutrient deficiencies when I kicked in CO2 suddenly at ~1200 during ~5th week, as well as lots of nanners popping up indicating stress.
In other grows with supplemented CO2 starting from week 1 or 2 of flower, it seems as though there are significant structural changes in the plants-- beefier trunks, thicker leaves, etc., that allow them to process the enriched environment, and without this adaptation during veg / early flower, they get 'burned' by throwing a bunch of CO2 at them mid flower. In future grows I hope to have CO2 gradually introduced from veg and peaked during late flower.

I'm still hoping for more feedback about temps. Assuming 85 is really ideal to take advantage of CO2 certainly is helpful in a sealed room, as it lessens the load my AC unit, especially when using a big propane burner to supply the CO2. Just wanna make sure that this 'rule' wasn't initially defined to help reasonably manage the natural tendency for a sealed room to run hotter.

 

[rambam]

Regarding temps and CO2 burners - isn't this one good reason to use compressed CO2? I don't know if its costlier, but to have the ability to add CO2 without adding massive BTU's of heat that you then have to cool, AND without the fire risk of having open flames unattended in your room for tens of hours at a time... Seems like an option to consider.

Just to add to your question about CO2's utility - I on the other hand have read that when using CO2 throughout the grow, you should CUT DOWN and not PEAK in late flowering. I'm not certain how CO2 is used by the plant, if it contributes directly to flower growth, or if the better bud growth is a secondary effect of improved vegetative structure, in a similar way that longer vegetation produces more bud sites, etc.

 

[Lazyman]

Well, adding CO2 tends to increase plant metabolism, so often more water is needed, which may mean you need less nutrients, sometimes more though (strain dependent.) The stomata on the leaves are usually opened more around 85* so they respirate heavier, taking in more CO2, etc.

Higher differentials tend to help with resin production and increase "purpling" in purple strains, rooms that are still at 75* dark temps tend to have difficulty turning all purple. I know my ChemDawgs would love a colder dark temp, but I still get some purpling in late flower even with 75-80* night temps (I have a negative diff. room.)

 

[DiscoBiscuits]

can anyone in sealed rooms offer any advice on what temps they find ideal for co2 supplementation and ideal nights?

 

[Lazyman]

Regarding temps and CO2 burners - isn't this one good reason to use compressed CO2? I don't know if its costlier, but to have the ability to add CO2 without adding massive BTU's of heat that you then have to cool, AND without the fire risk of having open flames unattended in your room for tens of hours at a time... Seems like an option to consider.

Just to add to your question about CO2's utility - I on the other hand have read that when using CO2 throughout the grow, you should CUT DOWN and not PEAK in late flowering. I'm not certain how CO2 is used by the plant, if it contributes directly to flower growth, or if the better bud growth is a secondary effect of improved vegetative structure, in a similar way that longer vegetation produces more bud sites, etc.

Well, there are ways around the CO2 heat now, even with gas-fired generators.

The water-cooled unit (Hydro Innovations' HydroGen) and ducted units that let you exhaust the heat without losing much CO2 are now available, so you're not restricted to tanks in high heat grows anymore. All of them are designed to cycle though, heat buildup gets bad if you use too small a unit and it runs constantly. Click here for a good CO2 grow room calculator, http://www.hydroponics.net/learn/co2_calculator.asp for my ~9K cubic foot room the HydroGen would run for 13 minutes to load my room up with
1200 ppm additional CO2, and would probably only run 3-4 times a night, and they claim 86% of the heat goes right outside with the waste water.

 

[Lazyman]

can anyone in sealed rooms offer any advice on what temps they find ideal for co2 supplementation and ideal nights?

I would say optimum is 84* lights on, 68* dark temps would be about perfect.

 

[Cheeb]

I use NG gas generators because I dont even want to think about having to haul tanks and refill, etc. I oversize them to my rooms so that they only run for a minute or so before turning off..not creating a ton of heat.

I'd recommend using a bigger generator that would run less over a smaller generator constantly burning the flame.

I've noticed plants being gased will take on more food and more water.. so be prepared to give them all you've got.

peace
cheeb

 

[*mistress*]

diff

diff

I'm trying to get insight about the best conditions to provide for a sealed environment with CO2 supplementation. I've read some differing suggestions for ideal day/night temperature. Does anyone have reference to published literature / studies to confirm the common suggestion of 85f day / 75f night for CO2 enhanced to ~1200-1500ppm ? I can understand why a higher daytime temp might be required to make best use of the enhanced CO2 levels, but why would having higher lights off temps (75 compared to the standard 65f recommendation for open rooms) benefit the plants, as there is no CO2 supplementation during the dark period?? Maybe it's just healthier to avoid too large a differential between day and night?
Any thoughts are appreciated.
thanks
Max

see this link for brief comparison of day/night temps. excellent reference: http://www.ces.ncsu.edu/depts/hort/greenhouse_veg/pdf/GrowingGHCucumbers.pdf [@pgs. 7, 36]
growing greenhouse seedless cucumbers in soil and soilless media

negative diff-day temp cooler than night temp

zero diff-day temp equal to night temp

positive diff-day temp warmer than night temp

differences in temps effect the growth and development of the plant, during the season. it is how they register maturation points in nature.
after all, annuals have only 1 season to produce flowers to make more annuals for next season. important for them to register how temps are to know how long season is/will be - and develop fruit accordingly.

if you are running c02, and high light levels, would keep the night temp as high as possible. preferably equal to, or even higher than day temps. this will facilitate the distribution of the energy acquired during long day of high light. reason for running supplemental c02 is to make plant grow stronger+faster. higher temps=faster metabolism.

light helps plant create+store sugar. this is occurring w/ c02 going + lots of photons on leaves (light). but plant distributes this sugar 24/7, so if temp is decreased during lights out, cannot distribute full supply acquired during day.

dehumidification very good during all of this too. transevaporation occuring 24/7 too. keep vapor pressure deficit high (low rh), and the plant will drink more water, trying to make surrounding air moist.

want plant to take up water from roots, w/ electrical charges (nutes), make sugar, put sugar away, split c02+water, release water into atmosphere, release oxygen into atmosphere, and get fruit bigger all @ same time....

so, higher temps facilitate greater metabolization. basically, making the plant do cardio; or maintain a high rate of vital activity. temps (ambient air; leaf; root) greatly influence how/what/how much plant functions.

they can tell 1 degree 'diff'erence in temp...

here, run 78-88* day+night. can get to 90's easy. as long as massive air flow (to carry away moisture produced by transpiring so fastly, due to greater c02 concentrations...+higher light levels...) is in effect, they will be fine w/ 80+ temps constantly.

in nature, there are regions where high mountain, low valleys, peaks, equatorial jungles, deserts, etc. make nights very hot - w/ days being hotter. the plants will adapt and thrive in their environment w/ such conditions...

may consider studying basic plant physiolgy. why do plants want c02? what do they do w/ it? how do they actually release water into the air - or draw it in? temps control much of this. if adding c02, should be familiar w/ higher temps. that is why it is added in 1st place - to make bigger-stroger plants. less effective w/ lower temps.

try keeping temps @ 85 day, 80 night. only dropping to ~60-65*f @ 1hr after lights on. this will make them thin they had long cold night. they normally dont stretch as much w/ warmer nights.

hope this helps. enjoy your garden!

 

[Hydrostatic]

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