olddirtybastard
Member
i always kept my humidity at 65% for as long as i could, gotta scale it back though depending on how fat the buds are getting
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Vapor Pressure Deficit - VPD and Nutrient Deficiency
- Thread starter Kcar
- Start date
Hmm... I'm skeptical, that's all I'm saying. I've personally seen plants grow with no extraction whatsoever - virtually zero VPD - and grow very vigorously. I'm not suggesting that a low vapor deficit can't cause problems, just that I'm not sold completely on the fact that this is what it is. I respect your opinion, but I'm not sold just yet.
The correct tense would be 'was' as it was almost 3 years ago.
I diagnosed, fixed the problem, and have run that same tent almost 18 cycles since then, without that problem. How much more proof would you require?
Here's what was happening. The lights would go out, the extractor fan would turn off. Within 15 minutes the plants would be dripping with water.
All 'night' long. Then the lights would come on the soaking wet plants. The light would heat the water, and that caused the pattern you see on the plants.
I run coco ebb & flow, so they got watered 3 times during lights on and had massive root balls. Those roots (water pumps) don't just shut off because the lights go out....
P.s. I see that you're going into other peoples threads and acting all 'I know better than you' and being argumentative. Don't bother, unless you'd like to be banned.
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No more proof that you corrected the environment. I believe you did and you have never seen the problem again. I just respectfully disagree that it was a direct result of high humidity.
Exactly. It's very likely that this is exactly what was happening and a much more plausible reason for that kind of striping. But that is something very different to low VPD being the direct cause.
It's an indirect effect; a symptom of the high humidity, if you like. It's definitely not a good environment to maintain, I fully agree with that. I just think the actual cause of the striping is where we differ. I completely agree with the second quoted text. It's much more likely imo.
I see you've just added this onto the end of your post.
You're referring to someone else who can't handle disagreement and who himself was recently responsible for the closure of a thread. I have no intention of discussing that.
learn to handle disagreement and differing opinions. I'm sure no moderator on this website will ban me for having a different opinion to the next man. This is not nazi germany you know.
Like I say, I understand where you're coming from in regard to the water on your leaves causing the burning, I think it's a more realistic cause of what is pictured in the first post.
Yes this means I disagree with you. Yes it means I think you're wrong. And yes I will openly say it.
It doesn't mean I am disrespecting you and it doesn't mean I am belittling you in any way. The truth is there are too many egos which are too easily hurt when someone challenges their judgement.
Challenge me on anything I say. Search my post history and find anything you disagree with. I'm happy for you to do so, provided you are willing to debate or argue it in a mature manner without stooping to personal attacks.
Thanks, and happy Christmas.
You're referring to someone else who can't handle disagreement and who himself was recently responsible for the closure of a thread. I have no intention of discussing that.
learn to handle disagreement and differing opinions. I'm sure no moderator on this website will ban me for having a different opinion to the next man. This is not nazi germany you know.
Like I say, I understand where you're coming from in regard to the water on your leaves causing the burning, I think it's a more realistic cause of what is pictured in the first post.
Yes this means I disagree with you. Yes it means I think you're wrong. And yes I will openly say it.
It doesn't mean I am disrespecting you and it doesn't mean I am belittling you in any way. The truth is there are too many egos which are too easily hurt when someone challenges their judgement.
Challenge me on anything I say. Search my post history and find anything you disagree with. I'm happy for you to do so, provided you are willing to debate or argue it in a mature manner without stooping to personal attacks.
Thanks, and happy Christmas.
I think what he was saying was that without extraction you would have had moisture everywhere no matter what temp the room was.
VPD determines transpiration rates, but the plants are going to release a shitload of water when the lights go out. You need to deal with that by either extracting the air or running a dehumidifier
VPD determines transpiration rates, but the plants are going to release a shitload of water when the lights go out. You need to deal with that by either extracting the air or running a dehumidifier
pretty much the same as the plants in post #1 in this thread
like a severe mag def
this is my 1st run in the new bloom room, sealed w/co2-->6-1000w lamps
i started seeing this as i got around to firing up the 5th lamp.and Rh was in the lower 50s, as the plants got bigger rh upped to 55-59% it seemed to stabilized... somewhat
and i had pulled also back on nutes, it didn't seem like they were being metabolized and started seeing over fert signs,
so it wasn't a nute availability issue.
the 6th bulb went online 4-6 days ago and rh bottomed @44%
now this mag def is back with a vengence.
since yesterday Ive been spraying water everywhere and Rh is in the mid 70s,
it seems to have stabilized again so it definitely seems to be Rh related.
i have a humidifier incoming soon...*fingerz croessed*
so if this is a lockout from VPD i need to know if i should start with some xtra mag in feeding
oh.. forgot,
I was also getting the taco leaf when low Rh was on, pics on the 1st page
like a severe mag def
this is my 1st run in the new bloom room, sealed w/co2-->6-1000w lamps
i started seeing this as i got around to firing up the 5th lamp.and Rh was in the lower 50s, as the plants got bigger rh upped to 55-59% it seemed to stabilized... somewhat
and i had pulled also back on nutes, it didn't seem like they were being metabolized and started seeing over fert signs,
so it wasn't a nute availability issue.
the 6th bulb went online 4-6 days ago and rh bottomed @44%
now this mag def is back with a vengence.
since yesterday Ive been spraying water everywhere and Rh is in the mid 70s,
it seems to have stabilized again so it definitely seems to be Rh related.
i have a humidifier incoming soon...*fingerz croessed*
so if this is a lockout from VPD i need to know if i should start with some xtra mag in feeding
oh.. forgot,
I was also getting the taco leaf when low Rh was on, pics on the 1st page
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Gnome, as you know, there are a lot of different reasons why a lot of things happen. It's hard to narrow it down sometimes. Variables are everything. It could be that the humidity in one situation wasn't right for the next. On the face of it though, those figures don't sound like they should be causing you such severe problems.
Have you got a dedicated thread about it?
Have you got a dedicated thread about it?
What figures?
Hes talking about VPD and only gave RH% without temp #'s...
If hes saying hes having a problem with VPD you have to assume his temps are mid to upper 80's.
Even at 60% hes still way below the ideal range.
At 45-40 hes having issues with uptake for sure...
Im sure his room is lit the fuck up and when you are sealed with co2 shit moves fast...
But yea... post a link to your thread here
i don't have a dedicated thread on this,
but posted this on 11-18 when i started seeing things were a tad not quite right.
https://www.icmag.com/ic/showthread.php?t=274937&page=2 post #26
also i'm running multiple strain and some are much more sensitive than others to the prob.
coconutz, what your saying is hittin the nail on the head, espcially on the Co2.
Ive had the same Rhs in my unsealed grows in the same place since 2010,
never seen these probs, but in the sealed room w/co2... its a prob!
at my temps i should be 70--75% Rh
@55-60%(25% from ideal Rh) is when i noticed things not right,
taco'ing, slight to moderate mag def on some strains, see link above
BUT
with Rh in the mid 40s im at nearly 50% from ideal and there's a *Definte prob that needs attention quickly*
see Kcars 1st pics in this thread
but posted this on 11-18 when i started seeing things were a tad not quite right.
https://www.icmag.com/ic/showthread.php?t=274937&page=2 post #26
also i'm running multiple strain and some are much more sensitive than others to the prob.
coconutz, what your saying is hittin the nail on the head, espcially on the Co2.
Ive had the same Rhs in my unsealed grows in the same place since 2010,
never seen these probs, but in the sealed room w/co2... its a prob!
at my temps i should be 70--75% Rh
@55-60%(25% from ideal Rh) is when i noticed things not right,
taco'ing, slight to moderate mag def on some strains, see link above
BUT
with Rh in the mid 40s im at nearly 50% from ideal and there's a *Definte prob that needs attention quickly*
see Kcars 1st pics in this thread
55-60% Rh in flower at 80f with CO2 is right where alot of
people like to keep it (Or lower) to prevent mold. Doesn't mean the plants
like it though. Also, check what's going on when your lights turn off. (30min after)
In my buddies 6K, CO2 levels and RH levels went through the roof after lights out.
Do you have any Dehumidifiers in there other than the AC? My buddy has 3 dehueys and a 3.5ton ac.
Together they fill a 55gal barrel each day.
What nutes are you using at what strength? Also, how many weeks in are you?
people like to keep it (Or lower) to prevent mold. Doesn't mean the plants
like it though. Also, check what's going on when your lights turn off. (30min after)
In my buddies 6K, CO2 levels and RH levels went through the roof after lights out.
Do you have any Dehumidifiers in there other than the AC? My buddy has 3 dehueys and a 3.5ton ac.
Together they fill a 55gal barrel each day.
What nutes are you using at what strength? Also, how many weeks in are you?
hi Kcar, thanks for starting this thread,
it gave me a quick heads up on what was happening.
since i started spraying a few days ago things have improved dramatically!
here's a pic of the strain that was most affected,
looks nothing like it it did 2 days ago,
Ive got 2 50pt dehuey's for the nite time Rh spike when the plants dump their Co2 and and water.
veg nutes are humboldts oneness, seamag-n-seacal, liquid karma and protetck silica and
at 1st i fed on the heavy side because i thought the Co2 would up the plants metabolism and they would take it but VPD started in
read this thread and backed off to water and LK only.
Im now giving them around 700-750ppms.
time in varies from 4 wks to 6 wks on the seed plants.
I'm topping this weekend,
getting cuts and into 12/12 in the next week
it gave me a quick heads up on what was happening.
since i started spraying a few days ago things have improved dramatically!
here's a pic of the strain that was most affected,
looks nothing like it it did 2 days ago,
Ive got 2 50pt dehuey's for the nite time Rh spike when the plants dump their Co2 and and water.
veg nutes are humboldts oneness, seamag-n-seacal, liquid karma and protetck silica and
at 1st i fed on the heavy side because i thought the Co2 would up the plants metabolism and they would take it but VPD started in
read this thread and backed off to water and LK only.
Im now giving them around 700-750ppms.
time in varies from 4 wks to 6 wks on the seed plants.
I'm topping this weekend,
getting cuts and into 12/12 in the next week
Gnome, chances are mate it's a simple case of overfert and backing off on the nutes is what's helped you more than anything.
The leaf curl you showed in that link is typical of low humidity, but the picture above looks like nothing more than a little bit of burn. If you've predicted a bigger draw on nutes because of the increased Co2 and have fed accordingly, and with silica in the mix, I'm 100% sure that's all it is.
That's got nothing directly to do with high VPD, but a knock on effect of it is the higher ec makes the tissue of the foliage more susceptible to burning at higher temps and lower rh.
The leaf curl you showed in that link is typical of low humidity, but the picture above looks like nothing more than a little bit of burn. If you've predicted a bigger draw on nutes because of the increased Co2 and have fed accordingly, and with silica in the mix, I'm 100% sure that's all it is.
That's got nothing directly to do with high VPD, but a knock on effect of it is the higher ec makes the tissue of the foliage more susceptible to burning at higher temps and lower rh.
Papaduc, I dont think you are seeing the connection between VPD and uptake.
Low humidity, or low vpd? A low humidity(45%) isnt going to cause that kind of damage in a cool room... But it will in a hot room with intense lighting and co2...
While his nutes may have been high for his conditions they probably wouldnt have been high under better conditions and may not have ended up burning his plants.
He already knows his plants are burned... What he is saying is he believes its related to the conditions of the room and I agree 100% because Ive never seen plants burn like that without an EC over 2.0 or some sort of problem with the environment or grower error.
Gnome seems like a competent gardener and is probably on the right path to correcting the issue.
Hes probably already rinsed the media enough to see if it was just buildup.
It seems like each one of your posts neglects key issues regarding VPD.
Have you read any of the articles being linked in the threads?
Im not trying to bust your balls man, it just seems like you should at least reread the material to have a better understanding of VPD.
