Fan Cfm VS Filter Cfm

1adamjb

1adamjb

Member
Hi all,
Right i just need to know if a 4inch 187m3 inline fan will work okay with a 5inch 360m3 phresh filter with a reducer?
I've been looking everywhere and it's just mixed opinions with some people saying u need a more powerful fan and a smaller filter
and other people saying the complete opposite.
Thanks in advance!
 
cc2012

cc2012

Well-Known Member
hi 1adamjb you will prob get a lot of mixed replies...but from what I read in lots of different Grow Books and Posts is more powerful Fan(CFM) than Filter size(CFM) also Ducting/Bends in Ducting and Reducer all add a load to your Fan and thus the CFM of Fan drops down(Quite a Bit) from the Stated CFM. How Big is Grow Room, What kind of Bulbs you running? all has to be considered - Me I bought way more powerful Fan than is needed, now just saving..to Build or Buy(would rather Build..seen Great Tut) Temp/Hum/Fan speed controller...

not 1 person on here will agree with each other though...not from what ive seen..and some can be quite rude...if so just ignore em...if someone wants to help they will do so without putting you down for asking or for Bad Grammar(Not You)....Lol

Peace

:peace:
 
1adamjb

1adamjb

Member
My grow is in a Pc case with an inline fan attached to a standard Pc fan exhaust so the amount of air i need to move is very small. The Pc fans cool it down on their own without the inline i just need it for pushing through the filter to clean the air. So you're saying i would benefit from a smaller rated filter and a higher rated fan? that made sense to me in one way that it will easily go through all the carbon in the filter but people were saying that you need contact time with the carbon so this is bad :S? Thanks ~
 
cc2012

cc2012

Well-Known Member
hi, with a Stealth/Pc Grow i'm not sure..but with that kinda size Grow I would say Less is better?? I take it you will be having Fan/Filter outside of Pc Case? and just to get rid of any smells? i've used Pc Fans for small Cab and also some nifty lil USB Fans of Fleabay quite good but just for circulation of Air.
Sorry can't be much help with this, but i bet someone on here got a Stealth/Pc Grow on the go..and can prob answer your question for you.

Peace
 
BatCave

BatCave

Well-Known Member
Filter CFM should always be matched and/or greater than the fan CFM. If your fan cfm is larger than the filter cfm you are sucking the air through the filter too fast and smells can get through. I run a 6" 440cfm fan attached to a 560cfm 8" filter and never have a smell problem.
 
puppetstring

puppetstring

Member
I think you'll have enough air flow for odor control but depending on the size of your space and what kind of lights you are using you might have trouble getting rid of heat.

cc2012 said:
hi 1adamjb you will prob get a lot of mixed replies...but from what I read in lots of different Grow Books and Posts is more powerful Fan(CFM) than Filter size(CFM) also Ducting/Bends in Ducting and Reducer all add a load to your Fan and thus the CFM of Fan drops down(Quite a Bit) from the Stated CFM. How Big is Grow Room, What kind of Bulbs you running? all has to be considered - Me I bought way more powerful Fan than is needed, now just saving..to Build or Buy(would rather Build..seen Great Tut) Temp/Hum/Fan speed controller...

not 1 person on here will agree with each other though...not from what ive seen..and some can be quite rude...if so just ignore em...if someone wants to help they will do so without putting you down for asking or for Bad Grammar(Not You)....Lol

Peace

:peace:
Click to expand...
hey bud can you post the link to this tutorial? I'm building something similar
 
1adamjb

1adamjb

Member
Basically i've got it set up like this at the moment with an old filter attached which isn't very good tbh, i tried using diy filters but they also failed me... so i do really need a correct filter this time aha (not really sure why my pics come out upside down)
DSC_0206.jpgDSC_0208.jpgDSC_0211.jpg
 
fir3dragon

fir3dragon

Well-Known Member
You want a filter with a CFM rating better or equal to your fan.

Example

6 inch 440cfm fan will work with a 440cfm or higher filter, but not a lower then 440 cfm filter

If you get one rated lower then your fan, smell will escape.
 
budskey

budskey

Member
always go filter size same cfm as fan or larger. if you go smaller filter than fan smells will escape. made that mistake not good wife could have killed me during last 3 weeks of flower cycle. never make that mistake again
 
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