VPD and nutrients absorption

[Scrogerman]

Nice One Sprurr, some really nice info for me to bookmark & work my way through, they'll keep me happy for a while. Yeah with the VPD, i figured the RH & Temps in my cab are pretty optimal for late bloom(74-78f & 42%RH Lights on) only a couple of weeks & its there, so happy dayyzz!
Great Stuff, Peace!

 

[spurr]

@ all,

Some people have told me they were unable to read the thread from ThecananCabana I uploaded on page one. So I compressed the HTML pages into a zip file, and encrypted it with the passphrase "ilovecanna" (without quotes). I uploaded it to a Russian file host, which is 'safer' IP wise than uploading it to a US file host. The Russian file host doesn't require Javascript, etc.

• http://www.file-upload.net/download-3019546/VPD.zip.html

 

[sorrendom_1972]

vpd.zip.html

vpd.zip.html

dear spurr i'd like to read VPD tread from TheCannaCabana, can you contact me ? i'd like you to mail me the file vpd.zip.html, because i can't download it from the russian site.
thank you

 

[Rolldaddy]

You can see our revised web site at* www.autogrow.com/joomla

There is a website one of our members gave me think to that has more info on vpd. I went back and fourth with him few times trying to figure out if having co2 would affect what the ideal VPD would be. From what I was understanding we want to be at a level of .85 kpa. From what their new website says .50 kpa is the ideal level to be at. To me it seems to be a little too high RH. Any thoughts on this
*

 

[noreason]

At 0,5 Kpa transpiration rate should be reduced, this is what I noticed in the last grows, but..... each crop is slight different, no? I mean tomatoes maybe do great transpiration at 0,5....cannabis needs a little higher VPD to do the best.

My two

 

[Rolldaddy]

.5 seems a little too humid IMO also. I was sharing the info

 

[Vintage1969]

Great thread thanks! I would have been running my humidity way to low for my temperatures, doing CO2 for the first time. I've taken the time to read up on VPD on the Internet as well

 

[R043]

Wouldn't want to necro but...

I was interested in the link posted by Spurr twice in this thread to a russian server

I downloaded it and it is an .EXE file hidden within the .zip

Antivirus scan online revealed a virus

Maybe a mod could deactivate the link or remove it (it is posted twice in the thread both time by Spurr)

DISCLAIMER :

1- I do not think Spurr had malicious intentions and the OP seemed at the time to have accessed a legitimate file. My guess would be some hacker bot searched for broken link to download sites and usurped the legitimate one most likely after it was removed by the original poster/owner.

2- My computer knowledge is limited. I do not state without a doubt there is a virus however it definitely seems like it and I always find EXE files suspicious.

 

[Baloni]

What is better with VPD??


A) canopy RH 65-72 canopy temp 28.5-29.5C
bush RH 70-75 bush temp 25.8-26.5C



B) canopy RH 45-55 canopy temp 26.5-27.5C
bush RH 55-60 bush temp 24.8-25.5C

 

[dcd]

Leave it to a bunch of newbies to bump up a thread from years ago... I find myself reading the older threads a lot too but don't know if I should bring them back. I've been trying to tame this beast.... I had weird yellow blotches on a couple of leaves that lead me to vpd. After they grew up n started transpiring more it went away. Dunno my vpd numbers but I have a dehuey in the lung room set at 55%. It seems to control the humidity in the tent good.... Right around 60% lights on around 70% with lights off. Lights on temps 70-75 down to a low of 60 with lights out. This is a higher rh than some but lowers than others. My plants seem to dig it and I have plenty of air movement to prevent pests.. It seems like the more water they use the more they grow so paying attention to how much they use lets me correct before there's an issue.. If they aren't using enough you have to add humidity or take it away assuming everything else is good. To me it just seemed like vpd was complicated to figure out and watching how much water they are using is relatively easy. Once I figured out what humidity they liked I use my fan controller to keep it where I want it... So far this has meant adding a little more flow to the vent fan but after harvesting I assume I'll have to turn the flow back down n maybe turn the dehuey off... I have a while before they see the cutters but I may lower rh just to be sure there's no issues even if it does slow em down. Hopin my veg can keep me from having to get a humidifier tho.

 

[EssentialGround]

my link4 controller is programmed to water based on the VPD...

The levels for RH disease suppression are only applicable if you have soluble ions, sugars or or unchained aminos in your plant sap..

 

[moses wellfleet]

keeping within VPD parameters is vital...

... It should be part of basic growing science, too many growers have never heard of it!

 

[MIERLU]

The VDP values are fine in bloom?