just answering a question based on an assumption as no specific specifications or dimensions were stated that he would be using one light in the average cupboard/closet sized grow, of course it does depend on room size and number of lamps used but its still possible with more than 1 lamp in a larger room, just by using larger fans filters and ducting with duct reducers at each cooltube site. The growshops always say this isnt possible coz they want u to buy two fans and two lots of ducting and so many people get sucked in by this thinking they MUST have two fans, but me being a shepered and not the sheep i said fuck you mr growshop salesman and did it anyway and it works fine summer and winter and i know its now common practice to run cooltubes in this configuration

Awesome thanks for the pics bro, you gave me some ideas as far as the configuration of the exhaust set up. Is that an 8" inline fan you got there?

Just for reference, the I'm thinking of venting my flower and veg room using a single filter and fan. THe veg room (10' wide, 6' deep, 6' tall) would have passive intakes. Next door, the flower room would have a filter and inline fan sucking air out of the room, through the lamp fixture, and out the exhaust vent. THe flower room (10'x6'x6') would have passive intakes leading in from the veg room. So, when the fan comes on, it forces (and filters) air out of the flower room, which causes air to be sucked in through the vents comingin from the veg room, which causes air to be sucked INTO the veg room from the outside intake.

So, I'm looking at using one fan to exhaust 720 cubic feet of air. So following the 5-minute rule, I'll need at least a 144 CFM fan. Subtract efficiency losses (2 passive intakes with sound/light baffles to suck through, then one bend in the exhaust duct to baffle light/sound), and I guess I need at least a 200-300 CFM fan.

ANyone wanna check my math? I do math for a living, so I'm used to unabashed criticism... you won't hurt my feelings!

Hi all. I'm building a can filter myself. Wondering if any experienced growers would know of a good fan cfm rating for this scenario.

I have a wardrobe grow in the works. I also have 4 ferrets.
My filter has a 4" inlet, It has 23" of filter length. The outer diameter is 6" and there is just above 1.5" of filter/media per cross section surrounding the inner core.
I have a moderately sized canadian basement apartment.

What cfm would be best suited to a 35cuft wardrobe and help a bit with the 4 ferrets in the living room.

PS: I was also debating using Silica Kitty Litter (clear stuff) instead of carbon

ok so you u have two equal sized rooms for veg and flower, to light both those rooms ideally you'd need 2x600w halides for veg and 2x600w hps for bloom, how come u only got 6' ceiling height with those sized rooms? I personally would keep the rooms intakes and exhausts independent of eachother, because the already heated air from yr veg room will cause you problems in yr flower room(drawing already warm air through yr cooltubes will greatly reduce their efficiency) that inline fan i use is 5" and pulls 240 cubic metres per hour, but my bloom tent is only 1.2x1.2x2m il let u do the math to convert that to cfm lol. id put yr 2 hps in cooltubes inline with maybe 3' of duct inbetween the two tubes then use the same configuration as me with fan and filter mounted to the top of yr room in the middle of the ceiling, blowing down to the cooltubes then out the room, and the same with the veg room using the halides, but id use a minimum of an 8" inline fan/filter/ducting for each room with duct reducers at cooltube sites, maybe even 10" because of the larger room sizes and two cooltubes per room. Ensure both rooms are sealed and airtight apart from yr passive intakes to ensure air is only being drawn thru the passives low down in the room and drawn over/thru the plants before it reaches the filter/fan. It is possible to extract/filter air from two rooms using one fan/filter but i wouldnt do it with the cooltubes, by using large passives in veg room then light baffled vents or ducts between the two rooms then use the biggest extract fan/filter/duct you can get on the outside of flower room sucking air thru both rooms and filtering by blowing thru the filter instead of sucking thru.

did u read any of the above posts? home made filters only last 2-3weeks if they work at all, without knowing the airflow rates(how much air can flow freely thru the filter before the filter creates too much resistance, and u need specialist airflow meters and pressure testers to find this out) of yr homemade filter it is impossible to match it with a fan, and using cat litter will not work at all! Cat litter is made to absorb large volumes of liquid over a relatively long period(a few seconds to absorb liquid is a long period of time) not made to trap microscopic odour particles from the air while being drawn thru the filter at a high rate via the fan. The only thing that works is pure virgin activated carbon designed for air filtration, not the type for water/aquarium filtration. Go to a growshop or order online a 4" inline fan/filter combo, that will be fine for yr drobe, and get a large box/bag of activated carbon online and refil yr filter every 12-18months or when the carbon is saturated and no longer works that wil save u some money, i think its the 3mm pelleted activated carbon thats used in most filters and works the best and widely available online. And how exactly do yr ferrets fit into the equation?

Ferrets get stinky some days. And the kitty litter isn't the clay kind if thats what you're thinking. It's a synthetic carbon substitute, just so happens it absorbs liquids as well Just like semi hardened granuals of ONO gel.

And I think the filter size will be ok, how can you knock something you've not seen? 2 weeks of usage? someone sounds grumpy. It's the same design as many on the net DIY & Purchase. just 4 inches longer.

And I was wondering on design and or brand names which work well. Not validation on my principles.

If anyone had better experience pulling rather than blowing. Inline or Axial

so far as Ive seen it, a 2 inch deep bed from inner core to outer core is what is commonly used when building a filter. The cfm of the fan really is based on air exchange ever 3-5 minutes. If you have a 1000 cubic foot room (10X12X8=960) you want a minimum of a 200cfm fan. That would just get you the 5 minute mark.

Now you do need time to filter the particles so on a 2 inch bed, you have one choice....... elongate the filter. Ever notice that the filters only get longer not so much different diameters?

I dont have an air speed formula because youd need to measure it but figure that you need 1 foot for say every 200 cfm and Id fudge that and go bigger just to be on the safe side.

I like these filters so much that I started building them to keep the regular smells out of peoples houses. I make a nice cabinet just for them. Unfortunately I have yet to find anything that makes them super silent but if you get used to the noise it just disappears into the white noise.

Run 2 of these in your house and youll never know you have animals or other odor problems.

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what about an ozone admiter how do those work for a grow of about 2-3 plants?

Ozone emitters are kind of sketch, I wouldnt use one unless you had to.

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i have seen many homemade filters made by friends of mine that simply dont work, u stated that u planned on using silica based cat litter, i can assure u this will not work, anyway u do whatever u wana do, and if u dont wana hear other peoples opinions then dont post yr questions on a public forum, and i really dont understand why people insist on being a skinflint and making their own stuff, things like building yr own hydro systems etc fair enough, but things like lighting extraction and filtration imo cannot be compromised on, i mean the amount of money growing yr own will save you, you can buy these things 10times over, instead of making yr own substandard shit.