Low RH in 3x3 tent. how to raise it?

madvillian420

madvillian420

Well-Known Member
As the title says, i just setup my 3x3 tent with a 4" 110 cfm exhaust fan and cheap flouro light for the time being. and so far, my humidity is steadily dropping, currently at about 43%. the tent is in a cramped space and i dont really have room inside or outside of it for a humidifier but i obviously need to raise that number. Is there anything you guys do to boost humidity without a humidifier?
 
Do you have plants in there yet? They raise the humidity some. Really without raising the ambient humidity outside the tent your gonna struggle to get RH up much. That said you can grow just fine in 43%.
 
Renfro said:
Do you have plants in there yet? They raise the humidity some. Really without raising the ambient humidity outside the tent your gonna struggle to get RH up much. That said you can grow just fine in 43%.
Click to expand...
not quite plants, i just put some germinated seeds in solo cups in there, waiting for them to sprout. my house is usually dry, so in anticipation for low RH i put plastic wrap over the cups with a few tiny holes poked in it. I appreciate the reply man, thanks for the help
 
Yeah for seedlings you definitely wanna dome them until they get some real roots going.

I think after they get bigger you will be ok, I have grown stellar crops in low humidity so don't fret.
 
Renfro said:
Yeah for seedlings you definitely wanna dome them until they get some real roots going.

I think after they get bigger you will be ok, I have grown stellar crops in low humidity so don't fret.
Click to expand...

hmm. how long do you usually keep them domed for? i could probably rig up some domes if need be. my plan was to uncover them as soon as i saw leaves but id definitely be willing to follow someones advice with more experience lol. and im glad to hear about the prospect of a stellar crop with semi-low humidity :clap:
 
I would keep a dome on them until they have their first set of multi bladed leaves. Then ease the dome off by opening the vents a little each day for a couple days before totally removing the dome.
 
madvillian420 said:
As the title says, i just setup my 3x3 tent with a 4" 110 cfm exhaust fan and cheap flouro light for the time being. and so far, my humidity is steadily dropping, currently at about 43%. the tent is in a cramped space and i dont really have room inside or outside of it for a humidifier but i obviously need to raise that number. Is there anything you guys do to boost humidity without a humidifier?
Click to expand...
You should have plent of space in a 3x3 for a humidifier. the entire footprint of your tent wont be covered by pots and if you're worried about getting the plants wet as they grow, use a piece of PVC directly above the humidifier to guide it to the top of your canopy to settle back do.

I domed my seedlings for almost 3 weeks, essentially until they had roots that held the soil and once they outgrew the dome i put them in their current pots.
 
You can find cheaper around but this is a good set up (you'll want a bit more lighting after first leaves show) and you will also want to raise the seedlings in the dome so they're a bit closer to the light.
 
yeah i should have thought ahead and got a dome. They just went in the cups today, i dont want to disturb them to transfer them, as well as already being over budget. my plan is to rig up some domes with cups like this: (not my picture, from google)
Cloning_Cups_1_1.jpg
 
madvillian420 said:
yeah i should have thought ahead and got a dome. They just went in the cups today, i dont want to disturb them to transfer them, as well as already being over budget. my plan is to rig up some domes with cups like this: (not my picture, from google)
Cloning_Cups_1_1.jpg
Click to expand...

That'd work great but I hope you have better lighting than them lol
 
I would not sweat humidity in the 40's or even 30's. That is where mine stayed all through the grow.
In a month or two you are going to be asking how to keep the humidity DOWN without letting the fan rip all the time.
 
madvillian420 said:
As the title says, i just setup my 3x3 tent with a 4" 110 cfm exhaust fan and cheap flouro light for the time being. and so far, my humidity is steadily dropping, currently at about 43%. the tent is in a cramped space and i dont really have room inside or outside of it for a humidifier but i obviously need to raise that number. Is there anything you guys do to boost humidity without a humidifier?
Click to expand...

ideally u want to shoot for 50% for growing but anything with in 30-50% is ok .........the really danger with RH is if it gets over 65% as Powdery mildew get going ......ad for drying and curing again 50-55% is the goal .......if the RH drops below 40 in drying u can get a hay smell to the stuff and if it gets over 65% molds can attach and grow


there is a simple way to raise the RH in a house with out using anything other then Baseboarder heaters........they are dry the air out alot but if u take several mason jars and fill about 3/4 with water then place them on top of the heater unit they will raise the RH slowlly but u will need to keep adding water every 2-3 days .............if that is not a choice then a hotplate/pic cooktop/ water kettle ......same idea turn them on low so the stream leaks out (pic cooktop 140f)........just have a fan blowing around to move the steam into the air

final part is a humitdifer ..........i know of this one and used it several years in my tent/room
https://www.amazon.com/gp/product/B009RGRHNQ

it is not like others it uses a fogger system to make the mist (ultra sonics to break water up ) .....the heat part will get it to the top of your area while the cool mist will keep it close to the plants ....it is digital u set it for 45-50% and it will get area up to that and keepo it there.....water change in 4x4x6 tent was every 36 hours in house RH of 32%
 
5BY5LEC said:
I would not sweat humidity in the 40's or even 30's. That is where mine stayed all through the grow.
In a month or two you are going to be asking how to keep the humidity DOWN without letting the fan rip all the time.
Click to expand...
Im just about 3 months into my grow and i still have to use a humidifer.
 
Ok. If you clear out foliage that will help keep your RH down too, when they get bigger.
If you must, I imagine a small humidifier like you would use for a baby would work well. Amazon also has a bunch of good ones.
 
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i appreciate the advice, thank you all. I set up my LED today and on top of battling a humidity now at 20, i have an in-tent temperature of 90-93. running a 4" exhaust on top of the tent but no intake fan. ive got a desk fan(11") on bottom near one of the tents mesh rectangular air vents, but it doesnt seem to be helping too much. pics of the fan and tent included to help visualize things.
71KouJj4ztL._SX425_.jpg
71pMktGGyRL._SX425_.jpg
 
Last edited:
In my 3x3 I have my light hood cooled buy it’s own 4” inline fan. Drawing air form outside the tent threw the the hood and out of the room.

Then I have a 6” inline on the t-stat. The comes on at 79*F.

In the 6” fan ducting I have a duct booster fan that runs non stop. So i always have a little bit of air flow.

Then I have a humidifier rated for 500sq/ft. Keeps the humidity around the 50% mark.
 
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