HELP! Help with high humidity

[CyberK]

Howdy! Started my first grow in a 2x2x4.5 tent about 3 weeks ago in a TS 600w grow light, FFOF/perlite soil, 18/6 schedule, 2 4" oscillating clip fans, 4" inline duct fan rated for max 200CFM, 17 oz dehumidifier. I live in a hot & humid state so really struggling to keep rH low. Currently temps and rH are in a decent range, 20-25C and 70-75% respectively. I know once the ambient temperatures in the room rise I will have a much more difficult time keeping them on track. I read the rH needs to be much lower for flowering to prevent mold. Haven't been able to get it below 60% so far.
Been reading a ton but hoping for some direct advice. Potable AC unit isn't really a possibility b/c we can't vent it out the window. Have a small swamp cooler to help with temps but, of course, that increases rH. Opened the side vents and top opening. Not really feasible to run the central AC in the house at a low temp.
I know I'm freaking out before I need to but I know there will be problems in the future. Greatly appreciate any advice you would be kind enough to share.
Much thanks!

[9fingerleafs]

You need a split unit in the room your tent is

[gbauto]

You would have better control of your RH if you condition your lung room instead of the tent.
I would also suggest you do some research on running your environment using a VPD chart to find the right balance of temp/rh.
https://pulsegrow.com/blogs/learn/vp...ect#chart-calc
I run led's in all of my grows and can tell you that you'll get much better growth if you can get your tent up to 28 degC.
I run my grows @ 65%rh during veg and typically don't run below 50%, even in late flower.
PM is best mitigated with airflow.

[YYCannabis]

gbauto ... you’re spot on.
If you can control the environment in the room the tent is in, it makes controlling the micro-climate in the tent a bit easier. Your VPD is important in climates that are dealing with high temps and humidity. If money is no concern, any issue can be solved, but most people are “growing on a budget” and need simpler solutions. Your current simple solution is to increase temp in the tent as mentioned by gbauto. Your big $$ fix is to get more ample environmental control for the lung room. A decent mid-price fix is adding an adequate dehumidifier.
One more thing to keep in mind...as your plant matures through veg the more moisture she transpires and raises RH even more. So some long term thinking and planning now will save more headaches later.

Are you exhausting the tent air into the room or outside?
Are you pulling air out from the bottom of the tent or the top?

A pic of your setup would help with ideas and solutions.

Cheers
YYC

[CyberK]

Really appreciate all the feedback. That VPD link is really interesting & helpful. Here's some photos. I know, a lot crammed into a small space. Will require lots of maneuvering as they (hopefully) grow! The de-humidifer is on the right. Would a larger or additiona de-humi help? I don't run the swamp cooler all day, only when the lights come on at 2pm until around 6pm. Pulling air from the top. Pointed 1 fan towards the light to try and keep it cooler and push the humidity up. Not sure if my placement on either is optimal. Included a couple of close-ups in case anyone has some feedback on how they're progressing. They (Amnesia) went into the soil 10 days ago.
Thank you!

[YYCannabis]

Not much can be done in a small space, and it’s going to get smaller as the plants grow.
That dehumidifier is probably not going to handle the humidity well enough, and you’ll have to empty it almost hourly. Having the hygrometer on the soil could be giving artificially high number, you could put it on a shoebox away from the plant for a while and see if you get different readings.

[CyberK]

YYCannabis Thanks YYC. Yea, gonna get cramped for sure! That little de-humi actually only gets dumped every few days that's why I was wondering if I need a bigger/stronger one (if that's a thing lol). Thanks for the hint on the hygro, I have 2 more I can place in other areas to see if I get a different reading.

[YYCannabis]

While your plants are wee little right now, they probably don’t mind the conditions at the moment. But in 4 weeks it’s going to be a different story for them.

Check out Home Depot website for portable dehumidifiers. If yours is 17oz unit and you are only emptying it every few days, i don’t have any faith that its working efficiently at 70% RH. (Maybe your numbers aren’t as bad as you thought since the meter was sitting on damp soil.) Even worse is the fact that it’s contributing to the heat in the tent and wasting electricity.

The logistics to solving this are finicky with your situation...small space; high temp; high humidity...ideally, you would take control of the macro-climate (aka lung room/bedroom/basement/shed...you get the idea) to help with controlling the micro-climate in the tent. What is the temp and RH in the room? Almost anything you do to the tent will be affected by the in-rush of air when your exhaust fan sucks the air out of the tent

Anything you do directly to the tent to control the climate will have an inverse negative effect on the other factors:
Option #1) Larger dehumidifier unit needs to recycle the air into the tent...the exhaust will be drier and warmer than the intake>>>temps rise in tent>>> Bad VPD depending on where your temps stabilize, but there is a range that would be within a good VPD spectrum.
Option #2) Portable AC unit needs to recycle the air into the tent...the exhaust will be cooler and higher in moisture than the intake>>>RH rises in tent>>>Bad VPD and mold inducing humidity.

And as I just previously mentioned, once your tent exhaust fan comes on, all the effort spent on the micro is lost due to the macro.

My best suggestions for your situation...spend the money on a large portable dehumidifier for the macro-climate. If you can get the lung room down to about 50-60%, then the drier air being pulled into the tent by your exhaust fan will help.