250 CFM fan through a carbon filter

I cant find this post that was on this site. Some dude was explaining about how your duct fan should have a certain rating, meaning it is prepared to push air through something. Trying to find out the rating so I can get the right fan.
Also, homedepot seems to only have 160 CFM fans - just checking their site. I couldnt, and nobody could direct me to duct fans last time I was at home depot, so. These fucking fans are bugging the shit out of me.

1) Whats the rating that basically says "This fan can blow air through something"?
2) Where is a good place to buy these fans other than home depot?

I just got a 265cfm blower from local hydro shop to replace the bath type fan I put in box. I used some formula I saw using watts x 3.16/temp diff (intake and exhaust)

example: I have 420 watts of cfl's a couple of fans and a timer so I used 500watts (the formula is supposed to be overkill)

500 x 3.16 = 1680

if the air outside my grow box is 75 and I want the inside to be 81 the diff is 6 so 1680/6 = 263.33

so I got a 265cfm blower. My box is 24 cu.ft. so the entire volume of air is changed supposedly every 6 seconds or 10 times a minute.

Well I would say get a big freaking fan cuz my box with the door shut would still be 90 so the door has been off but soon I go back to work and the lights are off when I leave and are on for 5 hour before I get home. I thought this big blower was going to solve the problem. Hope this helps! Wish someone had told me!

Shit. Does your box have an intake fan as well? Im going to be using 1 1000w cooltube HPS in a 104 cu ft room, and the box needs to be closed. Smell absolutely cannot escape.

Hayduke said:

I just got a 265cfm blower from local hydro shop to replace the bath type fan I put in box. I used some formula I saw using watts x 3.16/temp diff (intake and exhaust)

example: I have 420 watts of cfl's a couple of fans and a timer so I used 500watts (the formula is supposed to be overkill)

500 x 3.16 = 1680

if the air outside my grow box is 75 and I want the inside to be 81 the diff is 6 so 1680/6 = 263.33

so I got a 265cfm blower. My box is 24 cu.ft. so the entire volume of air is changed supposedly every 6 seconds or 10 times a minute.

Well I would say get a big freaking fan cuz my box with the door shut would still be 90 so the door has been off but soon I go back to work and the lights are off when I leave and are on for 5 hour before I get home. I thought this big blower was going to solve the problem. Hope this helps! Wish someone had told me!

Click to expand...

Sorry I meant to tell you I think it was cheaphydroponics.com had blower fans for well, cheap. I just decided to support my local guy who I also buy homebrewing supplies and get it now for a few bucks more than shipping.

I have passive intake so that all smell is vented into attic. The passive intake consists of 12 3/4" pvc elbows to stop light from getting in. The exhaust is 4" and the sum total of the intake is 9" with some constriction due to the elbows. Maybe I need more holes. As I understand it, if you have a fan force air in and a fan force air out, the max cfm would be that of the fan in so using a smaller intake fan would be worse than passive venting.

Looking at this
http://cheaphydroponics.com/store/imported-products/dayton-blower-265cfm/prod_151.html

So do you just mount it on a hole on the inside? Attach carbon filter to outside? Also, im no pro obviously, but it may be that your blower has a hard time pulling air from your box and those pipes. Maybe you need intake. Plus 4" is pretty small. Dont know how big this one is I linked to since the site doesnt say.

This is the same blower I have, mine is an EcoPlus, but I think they are made by the same. The square to round adapter I got is made by dayton and had the same logo as the ecoplus The square outlet is about 4" square. It could be mounted inside with square part to box or round intake down through top of box. I mounted mine intake down. i have pic on grow journal if that did not make sense (it's late)

I probably do need more intake but I figured if it was straining for air, it would kinda whislte. Cfl's are hot with the ballasts attached, probably shoould have done more research and got a 400watt hps they are so cheap on-line, but the cfl's are fun and kept close seem to work good.

oh and filter either in box or like in the attic. right now not an issue for me, when the seldom seen garden was in a closet with AC and no exhaust, it smelled nice. right now the attic is disbursing it, but i am rally small and only 3 weeks into flower. If it gets bad I will build a carbon filter or maybe a bathroom ionizer in the box? probably would not work or people would be recommending them.

http://htgsupply.com/viewproduct.asp?productID=46447

i just orderd two of those (one for flower and one for veg). i had 2 4in fans on out take, (one on veg and one on flower rated at 80 cfm) passive intakes, and depending on the room temp up to 93*F(if the room temp was 80*f the rooms would be 90* ish). hopefully 250 cfm outtake and 80 cfm intake will solve my problems once and for all.

my veg room is about 18inX36inX24in and i have a 400 watt metal halide conversion bulb at 3800 lumens. the flower room is 48inX19inX34in with a 400 watt hps light.

durbanpoison91 said:

http://htgsupply.com/viewproduct.asp?productID=46447

i just orderd two of those (one for flower and one for veg). i had 2 4in fans on out take, (one on veg and one on flower rated at 80 cfm) passive intakes, and depending on the room temp up to 93*F(if the room temp was 80*f the rooms would be 90* ish). hopefully 250 cfm outtake and 80 cfm intake will solve my problems once and for all.

my veg room is about 18inX36inX24in and i have a 400 watt metal halide conversion bulb at 3800 lumens. the flower room is 48inX19inX34in with a 400 watt hps light.

Click to expand...

This thread is pretty old, and I have lived and learned since the last post.

I no longer use passive intake...does not work without A LOT of openings.

Two other things that I would add....first those are booster fans meant only to assist a blower over long duct runs where the cfm's drop. and second, the exhaust is only as big as the intake...meaning if your intake is smaller than the exhaust, the actual cfm is that of the intake (assuming the space is somewhat air tight).

I have a similar flower space and no longer even attempt to keep it closed with the light on for more than an hour or two unless it is really cold in the house!