Too much air / Too little humidity

I'm working on my first grow and spent a lot of time designing my room. I went with a slightly oversized exaust fan (740 cfm) which I thought was a good idea.

Problem is I can't keep my room humid enough! I bought a humidifier but the exaust fan sucks the moist air right out. It usually hovers around 30-35% humidity but can even get below 30 sometimes. I decided to put some cardboard over the exaust hole to block some of the air going out but now I am worried about my fan working too hard. I've considered a fan speed controller but have heard those damage your fan anyway so i mine as well just partially block the exaust hole. Any thoughts / advise / suggestions?

is it just fan to outside? maybe get ductin and put it from your exhaust hole to your fan. put some zigza gs in the ducting and flow should decreace

what size is the room? i would just keep it partially blocked its no different than using a fan with a carbon filter or ducting which restricts air flow the fans life expectancy will just be lower, that or switch out your fans for 1 that you dont have to block... good luck

Dont worry too much.....when you start flowering you just might be trying to figure out how to lower ur humidity

well then he can just take off the cover and allow more air flow in and adjust accordingly which would be ideal to controlling the humidity to the level you want it

just put a T in the duct after the fan and redirect some back into room...for added moisture have the recirculating duct blow air acrossed the humidifier.

ive read to put a small pot of water in the tent. natural humidity. im still in the testing phase of my grow.

Put a humidifier by the intake of the tent....i had the same problem, it just sucks it out in veg. In flower though, I have it running full blast and it keeps it barely below 60 to low 60's.

I also find that periodically using a mist bottle and misting the walls and ceiling of the tent can raise humidity up from 30% to ~48%, going back down slowly over a few hours.

On top of the other suggestions stated above, hanging a wet towel in the tent can help as well.

-spek

sounds like you have great air exchange ,thats a good thing , dont hinder the air , just put the fan on a timer ,and experiment with a on fan off fan schedual, this will allow your humidfier time to build humidity, but watch your temp also.

there is a DIY here on turning a $5,00 24hr timer in to a min timer,this should work perfect in you case ,maybe start with 30 min on and go from there .

Thanks for all the replies everyone. I ended up purchasing a fan speed controller to drop the speed to 50%. The humidity rose up to about 40% so it definitely made a difference. I also put a fan near the humidifier - I was sure what effect it would have but the humidity has risen up to 48% now!

I had 4 recently transplanted clones that were looking like they were about to die. Since these changes they have made a full 180 and are looking great!

Btw - this is a 10 x 15' room with a 740cfm fan

You need a speed controller http://www.amazon.com/gp/product/B003URBQ1M/ref=wms_ohs_product?ie=UTF8&psc=1

I run a 6" fan about 1/3 speed with one of these and have perfect temp and humidity control.

Yep - that's the exact one I bought and I agree. It gives me great control over my room temp & humidity. Valuable little piece of gear.

AimAim said:

You need a speed controller http://www.amazon.com/gp/product/B003URBQ1M/ref=wms_ohs_product?ie=UTF8&psc=1

I run a 6" fan about 1/3 speed with one of these and have perfect temp and humidity control.

Click to expand...

what brand fan do you run? ive searched and searched for vent tech fans and being able to use a speed controller w/o burning the motor up. i came up empty handed. ive read some fans cant use a s/c and will burn the motor up in a few weeks/month. ive got (3) 6" 440 cfm fans i need to bring the speed down on.

I use it on this fan:

http://www.amazon.com/Hydrofarm-Active-Air-inch-In-Line/dp/B002JQ14F8/ref=sr_1_1?s=lawn-garden&ie=UTF8&qid=1366459563&sr=1-1&keywords=6+inch+inline+fan

Fan and controller are made by the same company, they guaranteed me the controller was designed to work w/all their fans

sweet, im sure it will work on the vent tech's. same fan design, im sure most all use the same motors, internals, just different branding.

how long you been running the fan with the s/c? does the s/c get hot when in use? ill be leaving my hood fans on 24/7 at prob 50% or less, and 50% for my carbon scrubber.

The fan w/controller has been running 24/7 for for about 2 months. I've got it outside the room sucking air through the tube. I called the company they said it makes absolutely no difference whether the fan pushes air into or pulls air out of a light/grow room. Neither fan nor S/C get hot at all, and at the lower speeds I use, it is almost silent.

sweet, thanks. i have my hood fans outside the tent, blowing air over the socket, then bulb, then out the tent. 6" 440 cfm fans hanging on rubber bungies hooked to my basement joists, i can barely hear them upstairs (unfinished basement ceiling).

People seem to get so bent out of shape about low humidity? Low humidity is not a bad thing at all, running under 50% in veg or even 40% does little to the plant other than speed up the metabolical rate allowing for more uptake of water and goodies. The problem is the grower not noticing the increase and starving them, this is where most growers have the issue and don't even know it!

My flower room right now is at 25% and if I could get her lower I would.

Air movement is the other issue with low humidity, wind wicks moisture off the leaves, so you only need minimal air movement. We all know already the leaves should just wiggle and not be getting ripped off by the wind. Don't blow directly onto the plants and you are fine.

Don't worry about low humidity, its the opposite that brings DEATH.