What type of fan for this cabinet?

Hey guys,

For a cabinet that measures
28.5" (W), 19" (D), 28" (H)

Which type of fan is needed? Lighting will be Blackstar 180w flowering LED, so not much heat.

Plants will be grown to 1 foot or less, with the recommended min 10" distance from the canopy for the LED. For plants that small, will smell become a problem? I know it depends on strain, but I have read, for example, that plants grown in a PC growbox don't smell much because they're so small. If 4-6 short plants were SOG'd in a cab with the dimensions I mentioned above, then would smell be minimal or it'll be a problem? What about twice as many plants grown smaller as a SOG, would that stink even less, or it'll add up to the same?

Was thinking of using a ball bearing PC fan for exhaust with no filter, just a light trap, with passive intake, and to make a DIY ONA bucket with a fan blowing into it and out of holes, in the same room but outside the cab, possibly running on a timer; would that be enough or I'll need a carbon filter? If the latter, then which one is the smallest and quietest that could still do the job? I had a larger one for a tent and it was like a jet engine! Surely for a cab this size, something much smaller and quieter will be needed

Thanks for your help!

This may be a good start. It's from another post I found on another forum:

Re: Calculate the CFM and fresh air duct size of your grow

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1.) Convert all inches into feet
Quote:
inches ÷ 12 = feet
38÷12=3.16'ft W (rounded up to 3.2)
28÷12=2.3'ft D (rounded up to 2.4)
42÷12=3.5'ft H
2.) Find the volume, feet cubed, of your cab.
Quote:
multiply Width × Depth × Height
W × D × H = feet cubed
3.2'ftW × 2.4'ftD × 3.5'ftH = 26.88'ft3
3.) Find for Exchange CFM rate. We want to echange the volume of the cab 4 to 5 times a minute. I will use the value of 5.
Quote:
feet cubed × 5 = Exchange CFM
26.88'ft3 × 5 = 134.4CFM
4.) Find for Additional Electrical Cooling CFM rate. Add all the watts of all equipment inside the cab.
Quote:
total watts of all equipment ÷ 4 = Additional Electrical Cooling CFM
250 watt light + 50 watt additional equipment = 300 Total Watts
300 Total Watts ÷ 4 = 75 AEC CFM
5.) Add the two CFM rates to get Total CFM
Quote:
Exchange CFM + AEC CFM = Total CFM
134.4 Exchnage CFM + 75 AEC CFM = 209.4 CFM
6.) Find the CFH (Cubic Feet per Hour) from the Total CFM rate.
Quote:
Total CFM × 60 = CFH
209.4 Total CFM × 60 = 12564 CFH

7.) Find for the amount of carbon needed for the filter.
Quote:
CFH × grams per foot of activated carbon (0.36) = total amount of carbon required.
12564 CFH × 0.36g per ft = 4523.04g
8.) Divide the amount (in grams) of total carbon by the length to yield the radius quotient. This is done with 2.6cm thickness as a constant.

Whoa, that looks like too much math for me.

I wonder if this site gives the same answer....

http://www.littlegreenhouse.com/fan-calc.shtml

linguistofcunning said:

Whoa, that looks like too much math for me.

I wonder if this site gives the same answer....

http://www.littlegreenhouse.com/fan-calc.shtml

Click to expand...

I have only 8.75 cubic feet. So with the specs I've listed, would a simple computer fan and a DIY ONA bucket be sufficient if plants are kept under a foot, under an LED etc? Or do I have to go the carbon filter route, which is louder and more expensive? The area is about 3.75 sqft, so I'm thinking I could SOG 4 to 8 plants comfortably. What do you think?

Hey guys, I just received my new Blackstar LED this morning (wow is it ever bright!), and I'm getting antsy to get started. Can anyone answer my questions please? Thanks!