How to raise humidity w/ ventilation

[mikessong]

How do you raise the humidity if you're constantly venting heat out?

I grow in a walk in closet with a 1000W in an air-cooled hood venting out constantly through a 465 cfm Vortex. This gives me perfect temps (80) but very low humidity (10-20%). And I have a humidifier running constantly on high blowing right on the plants. But the humidity stays low, especially if I have the A/C on in the room the closet draws from, which I need on sometimes to cool the grow room or at the moment to cool and dry my bathroom where the last crop is hanging! These new plants were healthier just a day ago when they were under fluoro's and 70% humidity because I didn't have to vent out the heat. So how do I raise the humidity? I thought about purchasing a fan speed controller, but I feel like any amount of constant ventilation is going to kill my humidity. So how do you guys do it?

 

[Guest]

SON-----------------you need to slow down. Look at what you just posted. How in the Hell is anyone supposed to understand what you just said?

Give it another try, slowdown and address the issues-----------there are a whole bunch of good folks in here that can help.

Ty

 

[mikessong]

My first sentence was a pretty simple summary of my issue:

How do you raise the humidity if you're constantly venting heat out?

 

[Guest]

I am still reading, over and over, what you said.. You have a humidifier blowing ON the Plants? and an AC unit running? does your AC have a drain hose?

Ty

 

[Guest]

have you checked your humidity at lights out?...you are in flower with this? with a humidifier at that low crazy man...maybee bigger humidifier outside of the space next to your intake

How do you raise the humidity if you're constantly venting heat out?

I grow in a walk in closet with a 1000W in an air-cooled hood venting out constantly through a 465 cfm Vortex. This gives me perfect temps (80) but very low humidity (10-20%). And I have a humidifier running constantly on high blowing right on the plants. But the humidity stays low, especially if I have the A/C on in the room the closet draws from, which I need on sometimes to cool the grow room or at the moment to cool and dry my bathroom where the last crop is hanging! These new plants were healthier just a day ago when they were under fluoro's and 70% humidity because I didn't have to vent out the heat. So how do I raise the humidity? I thought about purchasing a fan speed controller, but I feel like any amount of constant ventilation is going to kill my humidity. So how do you guys do it?

 

[Haps]

Here are two simple passive methods, both evaporation. A simple dish or pan of water will add humidity to the air, more so if there is a fan blowing on it. You can also hang a wet towl, or a damp bed sheet on a clothes line rig, spray it with a mister or take it and wet it wring out and re hang as needed. This also works better if there is fan action involved.

Or ya can catch one of these, hehe.
H

 

[mikessong]

With the lights out, I don't have to run the ventilation, so I can bring up the humidity to 60, 70, whatever I want. But with the 465 CFM running in my 4'x4'x8' closet, a humidifier blowing on hi right on the plants doesn't even raise the humidity one percent. The humidity outside is 10% so that's the humidity in my closet. I also tried moving the humidifier right outside the closet by the intake and it didn't work.

I am still in veg, maybe a week more, so this low RH is killing me. I found one similar thread a few years back, and it suggests two options: getting a high-output fogger or reducing ventilation (by getting a fan speed controller.) Which or both of these methods do you think would work for me? I have a feeling that even if I had a 100 CFM fan and a high-output fogger, if I'm constantly sucking in low RH air it won't make a difference.

Surely a lot of people are dealing with the same issue so what do you guys do?

 

[SouthernSmoker]

I have had similar problems in the past and the winter sucks for me due to dry heat .
are you venting your hood from an outside source or drawing air right out of the garden ?

 

[Guest]

southernsmoker gave you the answer to your problem in his question

 

[mikessong]

brilliant! i think you're right and i'm about to try it. right now i exhaust from my closet to outside. yes, the hood sucks from the garden which has a passive intake that draws from the adjacent room. so you're saying hook the air-cooled hood directly to the intake from the other room? then my room would get pretty sealed up and that should enable me to control my humidity hopefully. i may find that i still need to give the closet a bit of ventilation for heat reasons so i'm not sure exactly how this will work best but i'll try it and report back...this gives me some possibilities, thanks.

 

[mikessong]

tried it, but no luck. the humidity did start to rise to 25 % (at least my hygrometer works), but the temp shot up to 90.

so i tried moving the duct so it took out just a little air from the garden, but the humidity disappeared again. that would be a similar setup to if i used a fan speed controller, so i guess that idea's no good.

so i'm left with one of those high output foggers - anyone use those? or any other ideas? i'd assume other people have similar setups to mine and have figured it out. or is it just physically impossible to keep a room humid when the weather outside is desert-like?

in 3 days the humidity outside is supposed to get back to into the 40's, so at least i'll be in normal range. unfortunately by that point my unrooted chemdog clone and at least one of my og's may die, but most of the others should survive.

 

[floppyfundanglr]

sorry i know how you feel i almost lost my seedlings. They fell over than i propped them up and watered them and they survived. But i have to constantly watch the humidity.

peace

 

[Guest]

So how do you guys do it?

I don't ever directly address humidity except lights out when I shut my ventilation off and use a dehumidifier and a heater or AC to control temps. I've got an open system and not much I can do about humidity. I always shoot for maximum air exchange while maintaining proper temps. I've had humidity range from not readable on the guage to 50+% and every harvest seems to come out great. I don't grow big cola style genetics so never worry about bud rot.

unfortunately by that point my unrooted chemdog clone and at least one of my og's may die

Are you cloning under a dome? Once rooted I've never had an issue because of low humidity.

Anyway...I see no need for a fogger in my situation. Either high or low humidity the crop always seems about the same.

 

[anonymiss12345]

How do you raise the humidity if you're constantly venting heat out?

I grow in a walk in closet with a 1000W in an air-cooled hood venting out constantly through a 465 cfm Vortex. This gives me perfect temps (80) but very low humidity (10-20%). And I have a humidifier running constantly on high blowing right on the plants. But the humidity stays low, especially if I have the A/C on in the room the closet draws from, which I need on sometimes to cool the grow room or at the moment to cool and dry my bathroom where the last crop is hanging! These new plants were healthier just a day ago when they were under fluoro's and 70% humidity because I didn't have to vent out the heat. So how do I raise the humidity? I thought about purchasing a fan speed controller, but I feel like any amount of constant ventilation is going to kill my humidity. So how do you guys do it?

A bigger humidifier is the short answer.
But by your description of the setup...ditch the cooling aspect of the shade. Run it open so that your venting and ac are only running for ROOM temp purposes...not because it has to for every minute that the bulb is on.
I bet your average RH improves if you do this....EVEN if the vent still runs a lot. Cuz your room will circulate better and your ac will run less overall.

 

[anonymiss12345]

Also, for the record...RH below about 35ish absolutely ****s with the ease of keeping healthy and vibrant plants that are about 5" or less in height under hid lights.

 

[Guest]

Also, for the record...RH below about 35ish absolutely ****s with the ease of keeping healthy and vibrant plants that are about 5" or less in height under hid lights.

I dunno...I never seem to have a problem maybe cause when the plants are smaller they're under fluoros or if under an HID, 400W, I have the light pretty far away. I'd agree that higher humidity really helps with growth of smaller plants and vegging and early flower but have not noticed any real problems.

 

[mikessong]

Well I've been experimenting for a couple weeks and I've found the humidity in my closet is almost completely determined by the outside air. A few weeks ago when our outside RH was 10-20%, the closet was 10-20%. The humidifier doesn't really add anything because I have to vent out the heat so rapidly. However, I've found that for the humidifier to at least have a small effect, I run it in the room the closet draws from, not inside the closet itself. But the effect is still pretty small, so I don't think a more powerful humidifier would add that much. Slowing down the ventilation might help a bit.

But for the last few weeks, we've lucked out with 50-90% humidity outside. Now my closet humidity is at least up to a normal 40-50% RH. The only thing that still confuses me is why with 95% RH outside, two windows open with fans blowing, a humidifier running 24/7 on full blast, the humidity still can't get higher than 40% most of the time. Where does it go?

 

[morgancola]

Well I've been experimenting for a couple weeks and I've found the humidity in my closet is almost completely determined by the outside air. A few weeks ago when our outside RH was 10-20%, the closet was 10-20%. The humidifier doesn't really add anything because I have to vent out the heat so rapidly. However, I've found that for the humidifier to at least have a small effect, I run it in the room the closet draws from, not inside the closet itself. But the effect is still pretty small, so I don't think a more powerful humidifier would add that much. Slowing down the ventilation might help a bit.

But for the last few weeks, we've lucked out with 50-90% humidity outside. Now my closet humidity is at least up to a normal 40-50% RH. The only thing that still confuses me is why with 95% RH outside, two windows open with fans blowing, a humidifier running 24/7 on full blast, the humidity still can't get higher than 40% most of the time. Where does it go?

I would say one thing to do if your not already doing it is DWC. It makes allot
of humidity my nature and works good too.!!

MC

 

[anonymiss12345]

I dunno...I never seem to have a problem maybe cause when the plants are smaller they're under fluoros or if under an HID, 400W, I have the light pretty far away. I'd agree that higher humidity really helps with growth of smaller plants and vegging and early flower but have not noticed any real problems.

Ya, I'm talking about 3-4" rooted cuts going str8 under 1K's....they just can't handle the low RH on top of all the other stresses at the moment...lol...so RH HAS to be kept up for the little Gals or they just cross their arms and get stubborn...lol

 

[Guest]

The only thing that still confuses me is why with 95% RH outside, two windows open with fans blowing, a humidifier running 24/7 on full blast, the humidity still can't get higher than 40% most of the time. Where does it go?

I've wondered the same thing. Many times I've seen it pouring rain and foggy yet inside the flower room the humidity rarely gets over 50%. One thing is for sure...as temperature rises, for the same air 'sample', humidity will fall. That's probably part of it.

or they just cross their arms and get stubborn...lol

LOL...whenever I'm dealing with babies I mist very regularly even in higher humidity enviros.