How I control VPD

After struggling with this for months, I have hit on a solution that seems pretty close to perfect.

I have an 8x8 sealed tent.
I am running a Whynter ARC-14S set to 75 degrees (it's really at 69, but it translates to 75 average in the tent).
I have a ALORAIR Storm LGR Extreme dehum that runs constantly - set to continuous.
I have an Ideal-Air Commercial-Grade Humidifier GSH75, humidifier. It runs on a smart plug.
I am using SensorPush sensors. SensorPush HTP.xw Wireless. I have two, I calibrate one while the other is working and swap them back and forth.

I write software for a living (see screen shot). I wrote it using Visual Studio C#, but I think you could pull this off in Access.

So. The sensor reads the temperature. My software calculates the humidity range for that temp for the VPD range I've assigned, hi and low.
The AC keeps it close to 75 most of the time.

I live in the South, and you guys know what kind of summer we have had.
Hence the handful of failures and the larger humidity range showing. But these are momentary spikes.
And I'm also convinced that the Good Lord wants to remind me I am not perfect and never will be.

The Dehum, as I said, runs constantly. When it gets close to the high VPD range (1.1 in the screenshot), the humidifier kicks in long enough to lower it to the lower VPD (.9 in screenshot).

Yes, that's right, I run the Dehum and the Humidifier at the same time. Seems stupid. Nope. More costly to stop and restart the dehum than it is to leave it running. That humidifer is a big fogger. Doesn't run long, ever.

Then the process starts over.

The humidifer is on a timer, actually. It turns on the smartplug, and turns on a timer that runs it long enough to force it to the lower range (the time it runs to do that is a setting, of course, as it may vary).

Any questions?

They sell controllers

DaFreak said:

They sell controllers

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Why would I pay for one when I can make one that does exactly what I want it to do? FREE?
And I dare say... better? I've written code for 25+ years and make a lot of money at it.

Stumay111 said:

Why would I pay for one when I can make one that does exactly what I want it to do? FREE?
And I dare say... better? I've written code for 25+ years and make a lot of money at it.

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this is very cool. Have you checked out any sonoff/tasmota builds? I would love there to be a nice grower library for these with CO2 sensors, temp, humidity etc. Write us some shit!!!

I get what you are doing but running a de-huey and huey at the same time really sounds counter productive.

It may be easier to run your temps closer or above 80f in summer, where the rh may settle more in your particular setup. That would hopefully mean you need to elusively add or remove humidity.

The VPD charts are one thing, but translating that to each individual grow with climates, varying unit efficiencies, foliage amount, watering amount, etc, is something else.


When you say sealed, do you mean co2 sealed, or just venting every 30 min or so?.

Stumay111 said:

Why would I pay for one when I can make one that does exactly what I want it to do? FREE?
And I dare say... better? I've written code for 25+ years and make a lot of money at it.

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Your computer and the interface was free and water proof? Very cool.

DaFreak said:

Your computer and the interface was free and water proof? Very cool.

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Hey I totally know what you mean about controllers existing. I have experience with both gavita and Trolmaster controllers. And both are expensive and to be honest suck. The Trolmaster specifically is frustrating because it has potential to do so much but they purposefully neuter the thing with shit software and force you to buy extra modules/relays. A Trolmaster like system that's more generic would be a true service to growing IMO.

MidnightSun72 said:

Hey I totally know what you mean about controllers existing. I have experience with both gavita and Trolmaster controllers. And both are expensive and to be honest suck. The Trolmaster specifically is frustrating because it has potential to do so much but they purposefully neuter the thing with shit software and force you to buy extra modules/relays. A Trolmaster like system that's more generic would be a true service to growing IMO.

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Oh yeah I dodged a bullet on that stuff, along with the fancy light controllers etc. I never had any issues with ink-bird controllers for heat/vent/humidity control along with EU regulation standard timers. Sure they are ugly, and require more plug sockets.. but $130 or so all in. Last time I was looking into getting ''better'' stuff, the gear was reaching the $1k mark. I've calibrate the ink-birds with bovida packs and lab thermometer, they have not drifted much and are very acceptable in accuracy, given the investment cost. I actually thought I was making a mistake going cheap on this stuff, but thankfully not.

I've never rated gavita tbf. When CMH was the craze, they were selling single end 315w units for over $1000, that's the last time I looked at any of their stuff. I guess shipping etc played it's part but cmon, even at $500 that's insane levels of investment, on top of bulb renewals.

Flowki said:

I get what you are doing but running a de-huey and huey at the same time really sounds counter productive.

It may be easier to run your temps closer or above 80f in summer, where the rh may settle more in your particular setup. That would hopefully mean you need to elusively add or remove humidity.

The VPD charts are one thing, but translating that to each individual grow with climates, varying unit efficiencies, foliage amount, watering amount, etc, is something else.


When you say sealed, do you mean co2 sealed, or just venting every 30 min or so?.

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Co2 sealed. The only way out is through the AC.

Yeah, running hum and dehum seems wanky. But it works.

I do not subscribe to the idea that running hi VPD during flowering is beneficial. Any VPD range that does not pass through 1.0 is useless. So says the science.

MidnightSun72 said:

Hey I totally know what you mean about controllers existing. I have experience with both gavita and Trolmaster controllers. And both are expensive and to be honest suck. The Trolmaster specifically is frustrating because it has potential to do so much but they purposefully neuter the thing with shit software and force you to buy extra modules/relays. A Trolmaster like system that's more generic would be a true service to growing IMO.

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Not sure why it should be waterproof. But the computer was in fact free, I have piles of old computers.

The software took a day to write and months to tweak.

I probably have what you describe. With about 15 mins of code I could include my drip irrigation.

Ive experimented with controlling all three. It doesnt work nearly as well.

DaFreak said:

Your computer and the interface was free and water proof? Very cool.

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The computer is from the pile of scrap I have, so yes, its free. The Interface in the picture is my home 70" TV. I watch TV on it so yeah. It didnt cost nuthin extra. Waterproof? WTF?

MidnightSun72 said:

Hey I totally know what you mean about controllers existing. I have experience with both gavita and Trolmaster controllers. And both are expensive and to be honest suck. The Trolmaster specifically is frustrating because it has potential to do so much but they purposefully neuter the thing with shit software and force you to buy extra modules/relays. A Trolmaster like system that's more generic would be a true service to growing IMO.

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Oh yeah. I have this software on GitHub. Not updated lately but I can and provide a link.

This thread is a few years old but worth the read.


All I am saying is you may be able to use the plants respiration rates in your favour, by increasing temp>humidity, rather than fighting humidity constantly. I may be completely wrong here (I don't use co2) but everything I've read by growers who do suggest higher temps are better. If that is not the case then do correct me, I just have not seen anybody suggest that under 80f with co2 is optimal. If 80f+ with co2 still is the case, then it stands as yet another reason to increase your temps, for better co2 use and less de-humidifier use.

I am not arguing with science, but what science suggests, and what your set-up can efficiently achieve are two different things.

If you are correct, and Co2 at 75f is fine, how do you counter balance any gains there, with the loss in electric by constantly using both de-huey and huey, along with increased wear and tare.

You did ask to be questioned, nothing personal ^^.

Flowki said:

This thread is a few years old but worth the read.

Coco Tree's

75%rh in late flower is kinda asking for pm and or botrytis. Yeah seems like OP dials it back to 80F/70RH in mid flower

www.icmag.com

All I am saying is you may be able to use the plants respiration rates in your favour, by increasing temp>humidity, rather than fighting humidity constantly. I may be completely wrong here (I don't use co2) but everything I've read by growers who do suggest higher temps are better. If that is not the case then do correct me, I just have not seen anybody suggest that under 80f with co2 is optimal. If 80f+ with co2 still is the case, then it stands as yet another reason to increase your temps, for better co2 use and less de-humidifier use.

I am not arguing with science, but what science suggests, and what your set-up can efficiently achieve are two different things.

If you are correct, and Co2 at 75f is fine, how do you counter balance any gains there, with the loss in electric by constantly using both de-huey and huey, along with increased wear and tare.

You did ask to be questioned, nothing personal ^^.

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Youre good, I did. As I said in my post, the humidifier is powerful. It runs 3 minutes every 15 or so to restart the range.

So its hardly constant.

That said, I agree with higher temps.
The reason Im where I am is because I have clones coming and I want the temp lower til they get some feet.

That may reduce humid time.

What kind of light are you using?

Stumay111 said:

Youre good, I did. As I said in my post, the humidifier is powerful. It runs 3 minutes every 15 or so to restart the range.

So its hardly constant.

That said, I agree with higher temps.
The reason Im where I am is because I have clones coming and I want the temp lower til they get some feet.

That may reduce humid time.

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Yeah for me it's about the most reward for the least cost, effort and risk. I didn't empty de-huey barrel once last run, although the space is only partially sealed with thermal venting.

Stumay111 said:

The computer is from the pile of scrap I have, so yes, its free. The Interface in the picture is my home 70" TV. I watch TV on it so yeah. It didnt cost nuthin extra. Waterproof? WTF?

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So if you needed to buy the TV, the computer and so forth it wouldn't be free then would it is my point. But yes, very cool that you can make that happen with the stuff you have around the house. And if you keep it in your grow room like a lot of people just do, they are made to be humidity/water proof. But again, very cool that you made it.

green_machine_two9er said:

What kind of light are you using?

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Spider farmer sf 4000, 3 of them

Flowki said:

Yeah for me it's about the most reward for the least cost, effort and risk. I didn't empty de-huey barrel once last run, although the space is only partially sealed with thermal venting.

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I went all out, dehum has a drain and hum feeds from my drip irrigation system.
And just in case, the lights are on an temp controlled switch in case it all blows up at night.

I work from home

Stumay111 said:

hum feeds from my drip irrigation system.

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Hah, if it works why not. Good luck with figuring it all out.