Design Flaw in my room? Is RH Fluctuation causing stress? (If so, how to fix)

I've set up my grow room in a small 4x4x4 space with a 8000 BTU aircon (non-inverter type).

When humidity or temps get too high, the aircon and dehumidifier kicks in.
This rapidly dries out the air in the room. Then the humidifier gets triggered to bring it back up again.
RH is normally around the average of 65% (seedlings/early veg) target but it can get as high as 80% or as low as 40% in one day, or even in one hour due to the action of my aircon and humidifier.
I've tried to minimize this and even it out, but it might still be causing terrible stress?

My question is, could that be causing the yellowing seeing? If so, how can I mitigate this design flaw?

Looks like it's you not environment

Medium
Nutes
Ph

Etc etc etc

I am working with a few different seed starter soils now to finally rule out those variables (medium/nutes/pH).

Now I am planning on easing those into the super soil when ready by having 5-6 nodes with about 7 inches tall. And will layer the super soil so it can really ease into it.

I think the soil/substrate mixes I made, or super soil I burned them with earlier and each substrate's organic nutes or lack thereof were problematic I think.

As opposed to store-bought starter mixes/soils. I do agree it could have been causing the problems we see now. Along with over/under watering etc. Which is why I am continually testing and adding new seedlings until I get this sorted. And watering much less than before.

Anyways thanks @BobThe420Builder

So I can likely rule out the environment question and focus more on my own over zealous human intervention flaws

BobThe420Builder said:

Looks like it's you not environment

Medium
Nutes
Ph

Etc etc etc

Click to expand...

Just to be clear, you do NOT attribute the yellowing to RH fluctuation:

Frequent daily fluctuation between 55-75% while targeting 65%. With highs and lows often of of 40 and 80%.

They look like hell


I'd say it's YOU not the RH issues, but I'd try and fix that as well


Super soil is ruff for beginner growers, your going to have a struggle I'd say thru your entire grow

Damn what do you recommend for beginners indoors then instead of super soil?

Any recommended way to fix RH fluctuation? (Maybe I need to automate humidifier to turn on simultaniously every time aircon turns on so less delay?)

Looks like you've got a bit of dialing in to do, but I'd make sure your ac isn't blowing on the plants. Osmotic stress will do funky shit like that

Just grab some fox farm ocean forest. It’s all I used to use then add fox farm bloom once flower hit. If you could try hydro you’d be happy as well. I’ve heard people say it’s more complex but I wish I had started out hydro it’s much simpler than soil is to me.

I see a Co2 setup.

If you are using it, the plants could be getting choked out.
Especially being at floor level.

Roots organic original is amazing for starting seeds. Ive had excellent success.

Overgrowtho said:

I've set up my grow room in a small 4x4x4 space with a 8000 BTU aircon (non-inverter type).

When humidity or temps get too high, the aircon and dehumidifier kicks in.
This rapidly dries out the air in the room. Then the humidifier gets triggered to bring it back up again.
RH is normally around the average of 65% (seedlings/early veg) target but it can get as high as 80% or as low as 40% in one day, or even in one hour due to the action of my aircon and humidifier.
I've tried to minimize this and even it out, but it might still be causing terrible stress?

My question is, could that be causing the yellowing seeing? If so, how can I mitigate this design flaw?

View attachment 4719871
View attachment 4719872
View attachment 4719875

Click to expand...

Those are some pretty drastic swings in Rh.
By the looks of the picture, I assume you’re running a closed system, no exhaust. Is your ac connected to your temp controller? And is your dehuey/humidifier connected to your digital hygro controller? In a closed room, you’re gonna need more than just that 1 fan. Might wanna invest in a couple oscillating stand fans, 1 in each corner, get the air moving, this will help regulate temp/humidity. Wouldn’t be a bad idea to get some cO2 going in there as well.

I wouldn’t stress over the leaves turning on you that have been cut. Those are destined to die anyways. As long as your new growth is coming in decent.
As stated above more fans and and a controller on the dehu/humidifier should get the swings in check. I never worked in a sealed room so others may have better suggestions. I hope you get it under control

I'm not familiar with ac thermo/humidity stats but I assume that they'll be the same as a dehumidifier?

The lag/hysterious is really poor on my dehum, it goes to low then to high before switching on/off.
I've wired my one through a stc 3008 daul relay, it comes on at a pre set temp and off at a pre set, one side of the relay cools and the other heats.
That gives you the option to control heat and cold with 1 relay.
I've no electrical experience it's not difficult to wire a relay to a fan, dehum, heater etc and lets you maintain to within 1c.

The system when it is running should be fighting in one direction, not 2. While it is good to have heat and ac...humidifier and dehumidifier, 95% of the time only half the stuff should be running.

Having too tight a tolerance is what makes it keep fighting itself. Allow a range of several degrees and only have one system work to keep it there. Same for humidity. If its usually too low, set up the tolerances so it typically only adds humidity. At lights out, a dehuey running for a few cycles would be a worthwhile add on. But otherwise i think its just the setup of ranges.

lazaah said:

Looks like you've got a bit of dialing in to do, but I'd make sure your ac isn't blowing on the plants. Osmotic stress will do funky shit like that

Click to expand...

Yes when I first started the room they were blowing on but I've fix that a couple weeks ago.

BobThe420Builder said:

They look like hell


I'd say it's YOU not the RH issues, but I'd try and fix that as well


Super soil is ruff for beginner growers, your going to have a struggle I'd say thru your entire grow

Click to expand...

Anything in particular recommend for beginners indoors then instead of super soil? I used to run DWC two decades ago and found it smooth....

JoeBlow5823 said:

Roots organic original is amazing for starting seeds. Ive had excellent success.

Click to expand...

SmittyB.. said:

Just grab some fox farm ocean forest. It’s all I used to use then add fox farm bloom once flower hit. If you could try hydro you’d be happy as well. I’ve heard people say it’s more complex but I wish I had started out hydro it’s much simpler than soil is to me.

Click to expand...

No Fox Farm where I live in Asia. Yes I will experiment with Hydro soon...

TintEastwood said:

I see a Co2 setup.

If you are using it, the plants could be getting choked out.
Especially being at floor level.

Click to expand...

Too much CO2 I've ruled out since this problem was same with or without. I do use a regulator to keep at 1200 but the sensor is in the middle-height of the room so I guess the plants are getting about 1500 or so.

Dontjudgeme said:

Those are some pretty drastic swings in Rh.
By the looks of the picture, I assume you’re running a closed system, no exhaust. Is your ac connected to your temp controller? And is your dehuey/humidifier connected to your digital hygro controller? In a closed room, you’re gonna need more than just that 1 fan. Might wanna invest in a couple oscillating stand fans, 1 in each corner, get the air moving, this will help regulate temp/humidity. Wouldn’t be a bad idea to get some cO2 going in there as well.

Click to expand...

Yes using co2 now.
The USB fans I have, turn off for some reason, occasionally. They are not made for this. I've ordered two more that hopefully will be better.
Yes temps and humidity are all going through my controller in the cloud based on hydrometer.
I do think the fans are the best idea. Maybe I should have totally 4 small fans so that all air is mixed well and then the fluctuations wont be so bad.

Star Dog said:

I'm not familiar with ac thermo/humidity stats but I assume that they'll be the same as a dehumidifier?

The lag/hysterious is really poor on my dehum, it goes to low then to high before switching on/off.
I've wired my one through a stc 3008 daul relay, it comes on at a pre set temp and off at a pre set, one side of the relay cools and the other heats.
That gives you the option to control heat and cold with 1 relay.
I've no electrical experience it's not difficult to wire a relay to a fan, dehum, heater etc and lets you maintain to within 1c.

Click to expand...

Interesting about the relay. I am using smart home devices to do a similar approach however via Wifi.

ComfortCreator said:

The system when it is running should be fighting in one direction, not 2. While it is good to have heat and ac...humidifier and dehumidifier, 95% of the time only half the stuff should be running.

Having too tight a tolerance is what makes it keep fighting itself. Allow a range of several degrees and only have one system work to keep it there. Same for humidity. If its usually too low, set up the tolerances so it typically only adds humidity. At lights out, a dehuey running for a few cycles would be a worthwhile add on. But otherwise i think its just the setup of ranges.

Click to expand...

Agreed it would be counter intuitive to have the humidifier come on every time aircon comes on... seems too messy... but about the wider range... I am not sure it will help. I think I want to get the humidity range tighter so might therefore need to tighten the aircon range. (So the impact of dehumidification will be lessened when aircon comes on. I'll try this first....)

Overgrowtho said:

Damn what do you recommend for beginners indoors then instead of super soil?

Any recommended way to fix RH fluctuation? (Maybe I need to automate humidifier to turn on simultaniously every time aircon turns on so less delay?)

Click to expand...

Buy a proper separate Hygrostat. Move your dehumidifier further away from the growing area.

My best tip is to first of all learn all the basics for plant nutrition. Better your watering techniques. Like other people say supersoil is not for beginners.

Don't let humidity be your first priority. You should not spend time, money and effort on CO2 enrichment when you don't know the basics and lack growing experience. People grow healthy bulky trees outside without any climate control and CO2 enrichment.

Developing growing experience takes a long time and you should always work for improvements. Slowly work yourself up the knowledge ladder, develop experience and set your priorities straight. First things first.

Wastei said:

Buy a proper separate Hygrostat. Move your dehumidifier further away from the growing area.

My best tip is to first of all learn all the basics for plant nutrition. Better your watering techniques. Like other people say supersoil is not for beginners.

Don't let humidity be your first priority. You should not spend time, money and effort on CO2 enrichment when you don't know the basics and lack growing experience. People grow healthy bulky trees outside without any climate control and CO2 enrichment.

Developing growing experience takes a long time and you should always work for improvements. Slowly work yourself up the knowledge ladder, develop experience and set your priorities straight. First things first.

Click to expand...

I've succesfully done outdoor grows with this same super soil and used to be into indoor DWC many years ago. I've read Jorge Cervantes book and am half way through Ed Rosenthal's. I have done a good amount of research but this is still my first indoor soil grow.

I see your your guys point that supersoil is difficult.... Others say that supersoil is considered good for beginners since all they have to do is water and not obsess about feeding or pH.

What form of growing to do you recommend IS BETTER for beginners?

I might start to play around with DWC again (just got a setup in the mail) but at the moment I'm pretty committed to making this work with soil.

I know, I need a bit more patience. Need to slow down and smoke a joint. This has been frustrating to only get dead or sick seedlings.

I'm sure it will turn the corner eventually with improved substrate and water/nutrition approach after breaking this impasse....

...I've moved the dehumidifier up to a higher elevation in the room so it could be more effective... I'm pretty sure my current hygrostat smart wifi sensor is fine (hydrometer). I have 3 others in various spaces in the room.

Ive done SS from Day 1. It is of course critical that the soil be made well enough that it gets through a grow the first time, otherwise....

But the good part is, once that first run is done you can start tuning the soil by how it is amended. I personally think it is or would be the easiest method, which is why I did it. No adding nutes, just monitoring for changes and yellowing while watering carefully.

ComfortCreator said:

Ive done SS from Day 1. It is of course critical that the soil be made well enough that it gets through a grow the first time, otherwise....

But the good part is, once that first run is done you can start tuning the soil by how it is amended. I personally think it is or would be the easiest method, which is why I did it. No adding nutes, just monitoring for changes and yellowing while watering carefully.

Click to expand...

What medium did you start in to avoid burn? What method did you settle on for watering quantity and regularity for seedlings / early veg? For yellowing what did you change?

Relays... you can have whatever you want switching on/off at whatever hi/lo temperature you want, between the two relays they can maintain a room temperature to within 0.3/40c actively heating or cooling, they can switch anything you want on when it reaches x and cooling until it reaches x, or switching on when it falls to x and heats to x...Around $15
I turn my dehumidifier right up and let the relay control it.