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Thread: I think I GOT IT

  1. #1
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    Default I think I GOT IT

    I would like to get a growlab 120 which is 3'11''x3'11''x6'7''. I want to use a 600 watt air-cooled light. I was having trouble figuering what size fan and filter I needed for this size tent. I think I got it,what I got was 50.4 cfm.Can someone tell is this right.THANK YOU for any help. I used the formula in ventalation part 1.
    Last edited by blowdro; 09-11-2010 at 09:32 PM.

  2. #2
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    79"x47"x47"=174511 in^3
    (174511 in^3)x((ft^3)/(12^3 in^3))=100.99 ft^3
    100.99 ft^3 x 1.05 (5% for air cooled light) = 106.03 ft^3
    At the recommended one air 1 air change per 3 minutes:
    106.03 ft^3 x (1 air change)/(3 minutes) = 35.35 or 36 ft^3/min (cfm)

    You may have had some extra temp factor thrown in, I don't know. Apologies for the extended notation, just making sure all my units cancel out.

    Here's the calc with the max non air cooled rating:
    100.99 ft^3 x 1.15 (15% for air cooled light) = 116.14 ft^3
    At the recommended one air 1 air change per 3 minutes:
    116.14 ft^3 x (1 air change)/(3 minutes) = 38.71 or 39 ft^3/min (cfm)
    Last edited by brbubba; 09-13-2010 at 09:08 AM.

  3. #3
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    thanks brbubba

  4. #4
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    Quote Originally Posted by blowdro View Post
    thanks brbubba
    No problem, just double check my numbers for yourself and possibly add any other secondary factors. Good luck!

  5. #5
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    Brbubba I tried to come up with that answer but I still dont see how you came up with that thanks anyway by the way what does ^ mean is it a divide symbol.well I divided 3 into 36 and got 12cfm am I on the right track.
    Last edited by blowdro; 09-13-2010 at 03:25 PM.

  6. #6
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    Quote Originally Posted by blowdro View Post
    Brbubba I tried to come up with that answer but I still dont see how you came up with that thanks anyway by the way what does ^ mean is it a divide symbol.well I divided 3 into 36 and got 12cfm am I on the right track.
    That means cubed or cubic feet. ft^2, ft^3, etc.

    I converted your feet to inches for sake of simplicity and multiplied all the dimensions. Then I converted back to feet, 12 inches per foot, but you have to apply the cube to the 12 as well when dividing. This gives us the ft^3 or cubic feet of the space. Then we add the correction factor for your light. Once we have that 106 ft^3 we know we have to completely replace that much ft^3 of air every 3 minutes, so we divide that number by three.

    Here I used word equation editor so you can see it properly. Being a stickler on the units is a habit since it forces you to double check your work.

    Screen shot 2010-09-13 at 7.34.58 PM.jpg

  7. #7
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    brbubba if Iam thinking right then I should be able to use a 4 in fan and filter but will that be enough for the 600 watt light and the smell. thanks for all your help.

  8. #8
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    The filter will affect the calculation. As long as the fan is moving enough cfm then I am sure it would be fine. I'm not a ventilation guy, I'm just doing the calcs for you based on this site's guide.

    I don't know what you are growing, so I have no clue what smell issues you would have. If you want to know about carbon filters and ozone generators, I'm definitely not the guy for that.

    Again, I can help you with any calcs, but my growing experience is in areas that don't have ventilation concerns.

  9. #9
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    I want to grow tamatos and peppers to start off with then I will move on to other veggys I know peppers smell real bad. thanks again. This is the first time I 'm growing anything. So I'm happy and excited.
    Last edited by blowdro; 09-14-2010 at 06:36 PM.

  10. #10
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    Quote Originally Posted by blowdro View Post
    I want to grow tamatos and peppers to start off with then I will move on to other veggys I know peppers smell real bad. thanks again. This is the first time I 'm growing anything. So I'm happy and excited.
    Never really noticed any bad smells from peppers, hot or otherwise. I've grown habaneros and had bug issues, but no smell issues. Personally I think Tomato plants smell the worst. You are venting outside and not into your living room right? Seriously, if you take care of your system there really shouldn't be a bad smell. If you are still concerned about it down the road you can consult any of the "mary jane" forums which cover that extensively. I may not be into that stuff, but those guys do some damn fine work. With that in mind you might want to redo your calcs with a carbon filter in place.

    Taking that into consideration you are back up around your original estimate, about 45/50 cfm.

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