Questioning everything now... :(

Long story short:

I found out my main hygrometer slightly above canopy level was showing semi correct values.
It basically showed correct RH -5%, but it took hours to get there at high RH.
It also showed really dry values like 40%RH when the room I put it in actually had 50%RH

Given that I've been struggling with dying plants and pm in other grows, this makes total sense now.
I'm quiet pissed that I haven't really noticed this earlier, mbe I should have paid more attention.

I'm trying to establish a healthy environment for my plants now, but turns out since there were no apparent issues with the old hygrometer mbe like I went too far with the setup. I had like 16 plants in 3 gallon fabric pots in there (8x4 tent). Rarely seen any dew on my leaves but I had plants dying and also pm that killed a full harvest.

Bought new hygrometers put one in between the pots at the floor and the other slightly above canopy hanging in the center at the wall of the tent.
I turned air extraction up and put a second fan in there to have better airflow. RH still seems to be too high.
I took out 5 plants but it barely made a difference.

They're drying out quicker now, but the bottom RH still seems to be too high for too long.
(70 for at least a day after watering.) I'm not sure if it just looks this bad cause its the bottom of the tent, above canopy it's actually not too bad.
I was thinking it must have been crazy down there when I did SOG, and I never had these issues with the smaller plastic pots? Maybe if there's not enough room for vaporization down there the RH will move up quicker in the tent and not hold at the bottom?

My head is so fk'd right now, not sure what to do I can't get a dehumidifier right away...

Take out more plants? Repot in the old smaller plastic pots? I might even try drying those frickin fabric pots with some towels after watering, if I really have to LMAO.

what is the ambient humidity outside your house this time of year? the ambient humidity outside your home will influence the humidity in your home. in turn this will cause humidity of a higher percentage to be drawn into your tent by your fans. hopefully your tent isnt in a very large room. in your case i would likely have a room with the door closed and a very large dehumidifier cranked to the max then have a controller in the tent that can control the air flow based on the humidity of the tent. if the tent needs to be drier the controller will turn up the fan bringing in more drier air that you've created by having a large dehumidifier running in the room surrounding your tent.

Overpacked if I had to guess but I do dtw coco. Id do 8 plant max in there and thats not even my style, too small for each plant. I do 2.5x2.5 plants or 3x3. So that would spike rh having so many idividual plants dumping moisture. Or just too much foliage. The tents can only get so dry in that case. I use a half gallon worth coco per plant.

Stuffing 16 three gallon pots in there is Im guessing just as bad. If you leave a wet towel next to a hygro meter it tends to spike. You water all them and boom rh spikes, theres no real dew indoors unless it gets poorly cold. Thats gutstion and I just got done learning how it happens.

Those soppy wet pots cause increase root pressure given its not drying back properly. Vpd will play a role with that too. If night temps too warm its high motabolism happy in rootzone. So when lights come on to a high vpd warm temps it gutates to relieve that pressure from last night. Try cooling down the room at night and not so hot so fast during day and below a certain temp overall.

I solved PM with just a boxfan above a barlight pointing down at plants and exposing them to that air thru and thru shallow exposed canopy. I havent seen it 19 plants ago along with budrot after harvest in a couple weeks. It allows maximum space no obstructions to lights and should mix up the air in the tent better, allowing rh to even out. It will help speed up dry back and uptake so its not soppin wet and humid.

I dont measure rh below canopy but its probably not like that. Idk hope that helps.

xox said:

what is the ambient humidity outside your house this time of year? the ambient humidity outside your home will influence the humidity in your home. in turn this will cause humidity of a higher percentage to be drawn into your tent by your fans. hopefully your tent isnt in a very large room. in your case i would likely have a room with the door closed and a very large dehumidifier cranked to the max then have a controller in the tent that can control the air flow based on the humidity of the tent. if the tent needs to be drier the controller will turn up the fan bringing in more drier air that you've created by having a large dehumidifier running in the room surrounding your tent.

Click to expand...

Yeah I'm a little early, there's no heater on yet and we had alot of rain so 98% moisture outside.
All that and the fact that I'm roughly 10% higher in RH than what I thought I was.

2 Hours after watering I'm at:

70%RH ( floor, inbetween the pots )
62%RH ( at the stand of the fan, fans are raised about a foot )
64% RH ( in the middle of the long wall bout 2-3 inches above canopy )

Considering it has rained, I might get away with it, let's see how long it takes before it dries in there.
But I'll surely get a dehumidifier now for those rainy days.

Usually I'm nowhere near 12/12 by now, tried to be early and it's comin to bite me in the a...

When my setup was lacking and got mold it was only 45-55rh. Outside is always 80rh or more its always humid here. I dont see it as an issue as its my portable ac, it spikes rh.

In winter its humid and blowing cool air into grow room it cools it down without raising rh. So winter grows I have more control. Im still at 55rh this summer but its still fine if you keep awareness on rootpressure.

In winter I can get them to 35-40rh. I cant get it low enough on comand during summer the temps, its just more humid. I got two dehueys.

What's the ambient RH of the room the tent is in? And where is the air intake/exhaust for the tent coming from/going to?

420AD said:

Long story short:

I found out my main hygrometer slightly above canopy level was showing semi correct values.
It basically showed correct RH -5%, but it took hours to get there at high RH.
It also showed really dry values like 40%RH when the room I put it in actually had 50%RH

Given that I've been struggling with dying plants and pm in other grows, this makes total sense now.
I'm quiet pissed that I haven't really noticed this earlier, mbe I should have paid more attention.

I'm trying to establish a healthy environment for my plants now, but turns out since there were no apparent issues with the old hygrometer mbe like I went too far with the setup. I had like 16 plants in 3 gallon fabric pots in there (8x4 tent). Rarely seen any dew on my leaves but I had plants dying and also pm that killed a full harvest.

Bought new hygrometers put one in between the pots at the floor and the other slightly above canopy hanging in the center at the wall of the tent.
I turned air extraction up and put a second fan in there to have better airflow. RH still seems to be too high.
I took out 5 plants but it barely made a difference.

They're drying out quicker now, but the bottom RH still seems to be too high for too long.
(70 for at least a day after watering.) I'm not sure if it just looks this bad cause its the bottom of the tent, above canopy it's actually not too bad.
I was thinking it must have been crazy down there when I did SOG, and I never had these issues with the smaller plastic pots? Maybe if there's not enough room for vaporization down there the RH will move up quicker in the tent and not hold at the bottom?

My head is so fk'd right now, not sure what to do I can't get a dehumidifier right away...

Take out more plants? Repot in the old smaller plastic pots? I might even try drying those frickin fabric pots with some towels after watering, if I really have to LMAO.

Click to expand...

1. MANY hydrometers are crap, what are you using?
2. Quick fix, wrap your fabric pots with plastic or cling wrap or set them inside a plastic pot.

weedstoner420 said:

What's the ambient RH of the room the tent is in? And where is the air intake/exhaust for the tent coming from/going to?

Click to expand...

Anmbient is usually about 45-50%rh, if it doesn't constantly rain, currently 57%.

Air comes from the outside btw, gets pulled into the room, goes through the tent and filter and exits through another room.

I reorganized everything again in hopes of better airflow, both fans are rotating, so the middle column should be good as well.

• Blue fields with waves = air intakes
• Blue elypses with circle = fan1+2 (these ain't clipfans btw, the diameter of the fans is about a foot.)
• Grey & White boxes = Air intake that gets closed at night with a piece of round felt.
• Gey Pipes = Air intake with a hose, these stay open at night.
• The other two Air intakes are at the back and are constantly open.
• Black & White Circles = Plants

1212ham said:

1. MANY hydrometers are crap, what are you using?
2. Quick fix, wrap your fabric pots with plastic or cling wrap or set them inside a plastic pot.

Click to expand...

I had to improvise and bought 3 ThermoPro ones.
At least they show the same RH, what's the most accurate you know of?

420AD said:

I had to improvise and bought 3 ThermoPro ones.
At least they show the same RH, what's the most accurate you know of?

Click to expand...

RH is very expensive to measure accurately. The number that I've seen from Pulse is that their hygrometer is ±2% and is considered an industry standard (check their website, if you're interested, or that's a good question for chatGPT).

Calibrate your sensors. Run multiple sensors.

Don't forget that they're all "wrong". The question is "How wrong are they?"

To calibrate hygrometers, you can do the salt test or a 75% Boveda pack.

For thermometers, I use a Instaread thermometer that's been calibrated to 32°F and 212° F and then calibrate your other thermometers.

Once you have a sensor calibrated, you can "soft calibrate" other sensors.

I used an AC Infinity controller and a PulseOne in the tent, as well as 6 Govee's which I place in the canopy during a grow. I also use Acurite sensors in the garage, which is my lung room.

And don't forget to calibrate your IR gun, a requirement when doing VPD, and you'll need to set the emissivity of your IR gun, as well. The AC Infinity IR gun makes it very easy to set those values.

VPD is a big factor in nutrient imbalances. Fernandez (scienceinhydroponics.com) says that over 50% of nutrient issues are caused by VPD. Many growers will "solve the symptoms" either by turning down the light or slathering on CalMg, when the root cause could simply be to change VPD or change EC.

[edit]

"VPD is a big factor in nutrient imbalances" - in nature, VPD varies significantly over the course of a day so plants will handle short duration fluctuations without issue. A key thing to remember is that VPD is a huge driver of transpiration which is a huge driver of water uptake which is a huge driver of nutrient uptake (90% by mass).

If VPD moves up and down over the course of a day or so, the uptake of nutrients will vary and that's fine. What mucks things up with when VPD is too high or too low on an ongoing basis. If EC isn't adjusted to compensate for that, it's pretty much inevitable that nutrient imbalances will occur.

420AD said:

I had to improvise and bought 3 ThermoPro ones.
At least they show the same RH, what's the most accurate you know of?

Click to expand...

I'm not familiar with the ThermoPro. The best I've used is AC Infinity, it seems to consistently be within 1-2%. They use the same probe with both their controllers and the Cloudcom B1.
https://acinfinity.com/hydroponics-...-hygrometer-with-data-app-12-ft-sensor-probe/

This looks like another high quality hydrometer, suggested by duckduckgo.com search assistant. $70.
They also have both lower and higher accuracy versions for $55 and $90.

I just use caliber. Always been accurate.

I'm toast...

Even a third fan in there wouldn't change a bit at the bottom level, but as soon as I opened the door it went even with ambient.
Started smelling real good so it was just the air exchanging with the room.

So it's the combination of having too many plants in pots that hold too much water and not having sufficient air extraction.

500cfm would probably get me closer to ambient, not sure if my lung room wouldn't explode then with RH% due to 90%RH outside, tho.

So my only logic here, in case everything goes to sh*t, pick myself up and get me other pots.

11x 3 gallon = 33 gallon of soil holding water
8x 1.5 gallon = 12 gallon of soil holding water

That should make a difference, if that's not enough then there's only 1 option: a smaller tent and even less plants. :T

sux atm, seems like I cannot frickin win, just slightly underwater and pray the ladies are gonna make it.

I didnt pay much mind to possibility that exaust fan wasnt on max. Id hope so or thats for sure part of it too. I use s6 aci exaust fan on max 6” filter for 3x3 all vents open even duct ports next to vents. Any less and I would have rh issues. My 2.5x2.5 thats 6 ft tall has the same fan and filter even tho its smaller and even that could be better.

Maybe the fan isnt setup to run such large tent. Its a real large tent. Its just a bad foot print for me and anyone who grows like me, ur tent is like a bunch of 2x2’s put together. I hate 2x2’s they just aint big enough. So if exaust isnt on max Id do that. Maybe even get a 8” exaust fan/filter. Or break down to seperate tents which have loads if benefit isolating each plant.

Are you dtw coco? Its hard to do soil organic in small pots but if this dtw coco Id do half gallon to gallon worth of coco. I never saw more yield with 3 gallon then running as clones in half gallon/gallon worth coco. Much easier to take care of and they dont need root ball the size of a organic plant. Its a new plant with new rules, hydro. It dont need large root ball.