Carbon Filter Cfm Ratings

Discussion in 'First Time Marijuana Growers' started by R squaRed, Jun 10, 2013.

  1. #1 R squaRed, Jun 10, 2013
    Last edited by a moderator: Jun 10, 2013
    i have been reading up on carbon filters & have a few questions for those who know the correct answers. first off, i'm running a 2x3x7 closet w/400w hps and i have a 240 cfm inline 6" fan that i use the variable active air speed control at about 50%.
    i have read where the pro's say go with the biggest filter that you can afford. now thats what i have question about. the cfm rating the manufacturer puts on the different size filters. is this the operating cfm or maximum working cfm?
    now, if i'm running my 240 cfm fan at 50%, theoretically thats 120 cfm of air movement. now if i hooked that up to a filter rated at 400-600 cfm would it still filter odor effectively at only 100 cfm of flow, or should i buy a smaller filter(180-240 cfm) thats rated more inline with the amount of air i'm moving?
    i know if you exceed the recommended cfm the filter won't filter odor correctly, but what about going the other way? pulling less air than the recommended cfm's, will the filter still work as well?
    ive been told it will be just fine & ive also been told that since i'm moving so little air the bigger filters would pull air only thru 1/2 of the carbon bed closest to the outlet flange  therefore letting me swap the end caps on the filter housing(if possible on filter) to run the other end of the filter because it would still have fresh carbon. therefor allowing 1 filter to last twice as long.
    still i have other people telling me that if i don't move enough cfm's as filter is rated, that the filter will allow odor through because the air is going to slow through the carbon bed in the filter to remove the smelly particulates. is there any truth to that? please help me, as i'm about to buy a new filter for my closet and i would like to know will a larger 6x20" 420 cfm filter work well with only 100-120 cfm? or should i stick to a 275 cfm 6"x12" or a 375 cfm 6"x18"?
    between these 4 filters which would you get for a 2x3x7 closet with @200cfm inline fan with speed control...thanks blades
    Can 33 Carbon Filter 400 cfm
    Phat Filter 16"x6", 375 CFM
    Phat Filter 12 inchx6 inch, 275 CFM
    Phat Filter 20"x6", 450 CFM
    thanks again ahead of time blades..any links to threads covering this topic also welcome..
    *edit took out links, wasnt tryin to advertise, what i posted above will serve purpose thanks for heads up easternsmoker
    or maybe even use a 6x4 adapter and step down even lower to a 
    \tPhat Filter 8"x4", 150 CFM
  2. #2 aPersonUponaHill, Jun 10, 2013
    Last edited: Jun 10, 2013
    I am not sure we can post those links, I would check the rules carefully. 
    I'll be back tomorrow when not so tired to give a real response. 
  3. #3 R squaRed, Jun 10, 2013
    Last edited by a moderator: Jun 10, 2013
    thanks for heads up.i just listed the fans and took out the links.i look forward to your response! please every1 school me on how scrubbers/filters this pic it lists cfm for scrubbing, (one pass filtration)exhaust, & minimum cfm. can that be assumed of other filters from other manufacturers? say, 1/2 of rated cfm is an exhaust rating or 1/4 of rated cfm is the minimal cfm to be useful? thats the breakdown on this can-filter...
  4. #4 aPersonUponaHill, Jun 10, 2013
    Last edited: Jun 12, 2013
    Since its being funneled and with the constant force of air pushing the air infront of it and its mass will cause the air to be forced out of the carbon filter. However, the carbon/charcoal is packed together in there pretty tightly to ensure it functions correctly. So I would expect to half the max CFM rating rating and have it still work as desired, anything less, like 1/4, you might have smell issues. But really the only way to know is to actually test it, unless the manufacturer already did the work for you. But to offer you up some more advice, your space is fairly small, that 400 cfm filter you posted with the 100 CFM min would be fine. I mean jeez the space you have is what like 42(correction) cubic feet.
  5. This is old... but just so the answer is clear... you can use what ever fan you Want as long as you don't exceed the filters max cfm. So smaller is fine if that's all you need.... but too big of a fan... and the filter can not scrub the air in time..

    Happy growing
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