VPD in perpetual room

[Flowki]

Your not getting it!

The higher temps and the higher humidity. Open the stomata and allow the plant to in take more Co2. The high temp make the plant use more energy faster. The high light concentration of over 48,000 lux allows the plant to photosynthesize faster. These things allow the plant to "utilize" that higher available Co2 ppm.
No temps, no RH increase, and it's like wanting to go faster in a car without stepping on the gas pedal!

That help?

Do plants use enough of the natural co2 in normal conditions or could you increase rh/temp to allow them to use more?.

It's interesting since if you remember that other guys thread who's plants looked bad but budded like crazy, he said he gets like 90+ temps, has a lot of light and I'd assume that would increase humidity too, even if he is trying to keep it down (unless he isn't for that very reason?). But he also mentioned high night temps, maybe they were higher than day temps, somebody else commented on that being an explanation for the yield.

 

[Shugglet]

Your not getting it!

The higher temps and the higher humidity. Open the stomata and allow the plant to in take more Co2. The high temp make the plant use more energy faster. The high light concentration of over 48,000 lux allows the plant to photosynthesize faster. These things allow the plant to "utilize" that higher available Co2 ppm.
No temps, no RH increase, and it's like wanting to go faster in a car without stepping on the gas pedal!

That help?

VPD determines the stomatas actions. The only thin that your scenario would affect is a higher metabolism due to higher temps. The question is whether the plant is capable of photosynthesizing more light at higher co2 and light levels without increasing temps for a boosted metabolism.

 

[Dr. Who]

VPD determines the stomatas actions. The only thin that your scenario would affect is a higher metabolism due to higher temps. The question is whether the plant is capable of photosynthesizing more light at higher co2 and light levels without increasing temps for a boosted metabolism.

Question answer: No, it can not! All direct research states very plainly. That to have the actual benefit of that higher Co2 level. You must run higher temps and RH at levels determined by the available Co2 ppm concentrations! Lets not forget that you should be delivering about 48,000 lux to have that 1300 ppm work also! Light intensity, Rh, temps. These all need to be controlled properly to make any increase in Co2 ppm work!

1300ppm
48K of lux
88 - 91 F
78-80% RH

The sweet spot to make it all come together!

 

[Shugglet]

Question answer: No, it can not! All direct research states very plainly. That to have the actual benefit of that higher Co2 level. You must run higher temps and RH at levels determined by the available Co2 ppm concentrations! Lets not forget that you should be delivering about 48,000 lux to have that 1300 ppm work also! Light intensity, Rh, temps. These all need to be controlled properly to make any increase in Co2 ppm work!

1300ppm
48K of lux
88 - 91 F
78-80% RH

The sweet spot to make it all come together!

Can you link to any of this research? Rarely do I see humidity mentioned when discussing co2 supplementation.

Everywhere mentions higher temps but usually fails to amend the typical " ~50% rh" which according to vpd would be way too low.

 

[Dr. Who]

Can you link to any of this research? Rarely do I see humidity mentioned when discussing co2 supplementation.

Everywhere mentions higher temps but usually fails to amend the typical " ~50% rh" which according to vpd would be way too low.

That's it! You have to run that RH in proper VPD value when gassing! TO make that higher gas level work!

Look, I never really "sealed" the grow with the gens in it. I use environmental controllers to "keep" the whole thing running at peak performance. The controllers are set to exhaust at temp/RH limits I set. They go down a pre-programmed amount and the gen's kick in and raise the ppm back to my 1300 setting. The temps/RH rise and when they hit that "too much" start over point. It does...

When growing normally (I might be set to use gas but, don't...It is available if I ever feel the need) I run 70-72F and 35-40 RH. THAT is NOT a "proper" VPD value......The plant does better that way! VPD needs to be followed for gassing to work properly.

All three of the factor's work together. unbalance one and the effective use of the Co2 goes down...

Please feel free to google your own papers up on that! MJ growing sites are NOT good places for the science (or truth) on that! OH BUT, Ed Rosenthal does discuss and line it out in his Growers Handbook!

 

[linky]

I just want to know if ~75% humidity and low to mid 80's with 850-900 co2 will be okay in late flower/all the way through the cycle, to skurd to just do it

 

[Dr. Who]

I just want to know if ~75% humidity and low to mid 80's with 850-900 co2 will be okay in late flower/all the way through the cycle, to skurd to just do it

Yeah you should be ok there..
Everything increases with ppm increase...
BTW, you need over 84,000 lux for 1500 ppm.....Kinda hard to do! So 1500 ppm of gas is more wasteful then effective....

 

[linky]

Yeah you should be ok there..
Everything increases with ppm increase...
BTW, you need over 84,000 lux for 1500 ppm.....Kinda hard to do! So 1500 ppm of gas is more wasteful then effective....

I don't run it at 1500, anything over 1200 is a waste really anyway.. I run at it 850-950 generally.

 

[rickyb0823]

Shhhh, The VPD charting works best with gassing...

The best buds come from around 71 F and 35 - 40% RH

Interesting. I get my best results with 77 F and 50-60% RH with my co2 ppm set at 1450.

 

[Dr. Who]

Interesting. I get my best results with 77 F and 50-60% RH with my co2 ppm set at 1450.

Worked for me at 1Kppm

I had better at 88 and 80+

 

[davillains]

so I harvested my VPD through flower run and I had no mold except for a spot on a bud I had accidentally maimed.
My RH% was 60-65% during daytime and ~40-45% during nigh period where I had the exhaust running non-stop and good air circulation. I was running CO2 at 1300-1500PPM and I will definitively run VPD during flower again. I got 130grams dry from one 40day veg plant under a chinese mars hydro equivelant panel (~150w from the wall) and Dyna-gro FP from start to finish.

 

[mjinc]

I'm currently running my CO2 at 1200ppm, my temps at about 78F and humidity at 55%. Works a treat

 

[linky]

I'm currently running my CO2 at 1200ppm, my temps at about 78F and humidity at 55%. Works a treat

If you were going by the VPD chart you would want your humidity to be about 75% at 78F. Is that 78F canopy/leaf temp or ambient btw?

 

[mjinc]

If you were going by the VPD chart you would want your humidity to be about 75% at 78F. Is that 78F canopy/leaf temp or ambient btw?

I have looked at and I've seen the ideal VPD but it's really tough for me to reach. We have very warm days(at the moment) and cool nights so we find we get a ton of condensation if we keep the humidity too high. I also want to avoid ideal conditions for mold which can be a problem where we are.

 

[F1_Grower]

Gassing = The use of Co2 (it has to be run at high temps and matching Rh values)

YES! All through bloom! Be advised that 35-40% RH will cause more uptake! Feed accordingly!

The 70 F and 35-40% is not VPD "compliant". You get better/denser bud formation and it also helps keep PM at bay!

I'm in wk 3 veg.

Should I raise my temps?, rh sitting at 65 to 70% , temps 72 F light off 77 F lights on.

This is my first time hybrid loop. No exhausting outside but between grow rooms with FILTERED fresh cool air intake dedicated lines to each room.

 

[F1_Grower]

I'm in wk 3 veg.

Should I raise my temps?View attachment 4843346, rh sitting at 65 to 70% , temps 72 F light off 77 F lights on.

This is my first time hybrid loop. No exhausting outside but between grow rooms with FILTERED fresh cool air intake dedicated lines to each room.

Here is vpd with 4% lower rh, and slightly warmer. Or are you just describing grower secrets for last wk flower dropping rh like reintroducing 4200k bulbs? Ie terrine production, resins

 

[F1_Grower]

Question answer: No, it can not! All direct research states very plainly. That to have the actual benefit of that higher Co2 level. You must run higher temps and RH at levels determined by the available Co2 ppm concentrations! Lets not forget that you should be delivering about 48,000 lux to have that 1300 ppm work also! Light intensity, Rh, temps. These all need to be controlled properly to make any increase in Co2 ppm work!

1300ppm
48K of lux
88 - 91 F
78-80% RH

The sweet spot to make it all come together!

Hey Dr. Who,

I am very intrigued and curious as to what your research has uncovered. I am saving up for par sensor for my master controller but feel I've hit sweet spot, maybe not?

 

[F1_Grower]

I have looked at and I've seen the ideal VPD but it's really tough for me to reach. We have very warm days(at the moment) and cool nights so we find we get a ton of condensation if we keep the humidity too high. I also want to avoid ideal conditions for mold which can be a problem where we are.

Me too am having issues with condesensation forming on 10 x 6 x 9 atrium window which ppl could notice . Ambient temps 40F to 65F and RH 45% to 65% nor cal bay area