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VPD huey/dehuey controllers

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TreehouseJ

I'll preface by saying that the members on this site, past and present, have to be the most educated, resourceful, and tenacious group of rebel scum on the planet, and it breaks my little heart to know that over the course of a decade, either for being too stoned or stupid, I've been unable to retain more than a fraction of what I've read here and consequently wind up bibbing up and crying for a bottle on the forums. I sincerely apologize for my stupidity and the forum litter.

I hate to be this guy but, what are you guys actually doin' to control your vpd? My plants never scorch or burn at all for 3 solid months, until the end of stretch, and then they will start showing potash deficiencies from the top down..

My $700 cap xgc humidistat doesn't work for shit. It turns on at "80" and off at "70" regardless of relative humidity, so I'm weary of buying anything that hasn't been tried and tested here at the mag. Are you guys just dialing the onboard humidistat in your humidifiers to a working hygrometer, and manually adjusting every lights on/off? So many questions.. but I don't want to get ahead of myself. I'll just leave this here for now, I can hardly hear my own thoughts over this earache.

Alright.. so, coming back.. The RH in my basement where my tent is, stays around 50% humidity. My tent fluctuates between 55-70% in the 78f daytime, and between 55-60% during the 70f nights. Upper leaf surface temps stay ~82f lights on. Everything always stays uber green and burn free up until the nugs start to do their swelling, and then upper leaves will start wilting and curling. I didn't think I was that far off base. Is it possible that exchanging the 70% rh air in my tent for the 50% rh basement air one minute every 3-4 hours could be the culprit? Is 50% rh really all that low?! I'll have to post pictures later, lights are off.

Sorry if this belongs in the infirmary, I figured someone else maintaining vpd in a small tent might have some valuable insight sizing and controlling a huey/dehuey.
 
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ganjourno

Member
Your VPD sound fine, my guess would be you're going too heavy on the nutes. Curling top leaves sound like nutrient lockout due to overfert. What ppm are you watering at and in which medium?
 
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TreehouseJ

Your VPD sound fine, my guess would be you're going too heavy on the nutes. Curling top leaves sound like nutrient lockout due to overfert. What ppm are you watering at and in which medium?

I feed gh 3 part plus calmag @ half strength in 5 gallon dwc buckets throughout all of flower, and I add back with mainly just fresh water, and do lots of regular dumping. The plants love the same solution for the first 4-5 weeks of flowering, and then they start to burn. I'll be back with a photo in a minute.
 

linky

Member
Here is my humidity over the past 24 hours with that controller. I have it set at 77% (when lights on)

The 3% jump in humidity around noon is when my exhaust fan runs for 25 minutes to exchange air in the room (do this a couple times a day).


picture.php
 
T

TreehouseJ

Massive fail trying to photograph the canopy before the hps washed everything away. Everything on the bottom half of these plants looks fantastic. I'll try backing down on one of the girls next round to see if thats the case, but from what I can gather, this looks like the plants are transpiring faster than they should be. Perhaps there was some heat shock along the lines somewhere, or my hygrometer is off and we had a few dry days.. I donno. What I do know is that I want a fogger set up in there along with a couple more fans and a pair of reliable hygrometers before I turn everything around in a couple weeks. I run out of working space very quickly.
 

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T

TreehouseJ

Here is my humidity over the past 24 hours with that controller. I have it set at 77% (when lights on)

The 3% jump in humidity around noon is when my exhaust fan runs for 25 minutes to exchange air in the room (do this a couple times a day).


View Image

What are you using to chart your humidity levels? That's pretty BA. I wouldn't think that application is included in the $35 package, lol.
 

linky

Member
What are you using to chart your humidity levels? That's pretty BA. I wouldn't think that application is included in the $35 package, lol.

That is not part of the 35 dollar humidity controller lol, I am using this to monitor temps and humidity online, you can monitor remotely which is nice.

https://www.amazon.com/gp/product/B00ISKS8HG/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1

I bought an amazon warehouse one that was like new damaged packaging for 66 bucks.. its awesome as well, works great. Will email call or text you when temp or humidity is outside your alert parameters and so on.
 
T

TreehouseJ

What size lamp you running and how far from the canapy?

I'm running 2x600 w hps 6" cooltubes, and I'm pulling a ton of air through them. I'm only working with 5' vertical clearance so the nugs will reach ~12" from the lights when everything is said and done, but surface temps of the upper leaves don't get above 82f, and the fan leaves show consistent damage in ~ a 2' radius from both lights.
 

Vanilla Phoenix

Super Lurker
ICMag Donor
I used to run my plants really close to the lights and got the same damage as you. Temps were in good range too. I ended up backing the plants off of the lights, but can't for sure say that was it, cause I also tweaked my nute schedule at the same time.

Do you get signs of problems showing up in mid to top leaves first?
 
T

TreehouseJ

I used to run my plants really close to the lights and got the same damage as you. Temps were in good range too. I ended up backing the plants off of the lights, but can't for sure say that was it, cause I also tweaked my nute schedule at the same time.

Do you get signs of problems showing up in mid to top leaves first?

Yeah. Damage seems exclusive to the 2' radius surrounding the lights, everything on the bottom is looking on par. I'm thinking temps might have spiked one night while I was replacing my ac, and what I really need is a sensor that can monitor and chart my temps like linky is using, so at least I'm not playing guessing games or trying to change up a tried and tested nute schedule.
 
Here is another wireless solution that's a bit more affordable ($30 right now), though it has a yearly fee after 6 months if I remember correctly. I think its $10-15 a year/device. You also get an extra reading, temp/rH from the device and temp from the probe (6ft cord).

Mine have worked pretty well so far, I only have a few complaints. The wireless range isn't that great - I lose signal through two walls, a floor, and tent every few days for a few hours. The logs are only stored for a week, though you can pull them as CSV's which is nice.

https://www.amazon.com/gp/product/B0081UR76G
 
Also the LaCrosse can log data points every 5 minutes, where it looks like yours is every 30 minutes so you might be missing spikes which could make it difficult to dial in climate control.
 
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