Air Circulation Question

[halfdef]

Hello All,

I want some advice on air circulation. I have a sealed room, not perfect, a few small holes, but mainly sealed.

My room is a closet. I have an intake and an outtake fan running and since I am not running co2 at the moment I have the door zipped open a foot or so. I also have three fans in the room to circulate the air. I also vent my hoods.

My question is this, do I need to run the intake fan at night? I have been running it 24-7.. but I would like to run it just during the 'day'.

peace:banana1sv6:

 

[jansjukebox]

what you need to do is take a reading of your humidity about an hour before your lights turn on. If your humidity stays in check with the vent fan off then I say just leave it off unless you are running a charcole filter on it for smell protection.

 

[Jalisco Kid]

RH peaks just a few hours after lights out. JK

 

[Rolln J]

if your running a vented room (not a sealed room) the its best to keep the fresh air on 24/7

 

[ShorelineTex]

OMG...I was literally about to post this exact same question...

Instead of just turning off the fan during the dark cycle, could I cycle it to run, say, 20 minutes every couple of hours or so to just periodically refresh things?

(Running a small tent in a air conditioned room with consistently low humidity).

 

[DazedNconfussed]

I believe the formula your lookin for is (Length x Width x Height) that will give you your grow rooms total cubic volume. take that number and divide by 3 and that is how many cfm (cubic feet per minute) your intake fan sand exhaust fan should be. You want all the air circulated (at least in theory) every 3 minutes.

so i have a 5' wide x 6' long x 8' tall grow room giving me a total cubic volume of 240 cubic feet. So I want to circulate 240 cubic feet of air every 3 minutes requireing a 80cfm or better intake and exhasust fans.

I dont know this info is fact, but belive it is correct.....maybe a more educated farmer can chime in.

 

[ShorelineTex]

I believe the formula your lookin for is (Length x Width x Height) that will give you your grow rooms total cubic volume. take that number and divide by 3 and that is how many cfm (cubic feet per minute) your intake fan sand exhaust fan should be. You want all the air circulated (at least in theory) every 3 minutes.

so i have a 5' wide x 6' long x 8' tall grow room giving me a total cubic volume of 240 cubic feet. So I want to circulate 240 cubic feet of air every 3 minutes requireing a 80cfm or better intake and exhasust fans.

I dont know this info is fact, but belive it is correct.....maybe a more educated farmer can chime in.

This is for when the lights are on, right? Since there's no photosynthesis going on when the lights are off, do they need as much circulation?

 

[Rolln J]

no that formula is correct... but its not what hes asking...

 

[halfdef]

thanks for the feedback folks!!

jans RollnJ, thanks for the info!

RollnJ, I understand that fresh air is important, esp. to avoid mold.. but I`m guessing that it matters more during flower... so maybe i could turn it off during veg...?

Tex, glad that the thread helped, turns out that our space is nearly identical. I run a 180cfm intake and a 95cfm exhaust... my understanding is that this way more co2 will build-up in the room (COULD SOMEONE COMMENT ON THIS)..

anyone else want to add something new... come on folks..share the wealth!!

peace

 

[Rolln J]

humidity spikes when the lights go off - powdery mildew loves humidity spikes, so I never turn my exhaust off...

I dont run an exhaust and an intake fan - i have 2 passive intake vents and a 500 cfm fan for exhaust - if your pumping in more air then your venting out your odor control will not work as the air is gonna force its way out of your room through light switches/plugs/under doors etc...

you want there to be negative pressure on your grow area and you have positive pressure currently.

 

[muxee]

I have a veg room that sounds really similar to yours. I run my lights and fans on an 18/6 and I have never had any humidity issues (and I live in the Pacific NW, it rains here alot!) I do run my fans all the time in flower.

:hi: good luck with your room.

 

[halfdef]

well played muxee, thanks for the input!