What size fan?

Alright... So that's 40 cubic feet... Your air should be changed 3 times every 5 minutes... So that's 120 cubic feet of air to move in 5 minutes.... So 120 divided by 5 equals 24

Basically you need a fan that can do at least 24 cubic feet per minute(CFM)... I try to go for a fan that can pull 1.5 to 2 times what I need... My recomendation would be a 40-60 CFM and run it at about half speed

Just keep in mind that this is just a general rule for good air flow around your plants, if you're using HID lighting it's going to generate more heat.... So you'll need more air flow..... Flouros or CFLs don't generate much heat so you won't need as much air flow

Hope this helps

Forgot this... A computer fan of 6" or more should do it, just read what it's rated at for CFM.... It's available in any computer repair shop

If you want something more professional you could get an inline fan... Typically the small ones are 100 CFM, so you'll need a fan controller as well or you might be lowering your temp too much........... Inline fans can be found at any grow shop and sometimes at home depot....... to find your local grow shops... goto google maps, look up your city then type in hydroponics or garden supplies

 

I would not use a pc fan as they just dont have the grunt and the bearings tend to wear out quickly. Get something like this

Still i would go with a 5" fan high pressure inline fan they are only £40 - £50 and its a good investment. I would use the same but a 4" for the air in.

If the rooms are close together you can interlink the air in to save on purchsing 2 fans.

Hope this helps ya or points you in the right direction bro.

 

For stealth cabinets PC fans aren't too bad, actually, they're almost perfect..... What your suggesting is overkill for the size of his space

I think you need to read his post more carefuly, you were talking about rooms in your post, he's clearly talking about stealth cabinets in his.

To the OP... If your cabinet isn't air tight, make sure you have less air being put in by your fans than what's being taken out, this will help contain the odors by keeping the cabinet at a slight negative pressure.

 

Bro Ime just going by experiance and I dont think its overkill as i had a bathroom extractor fan for my veg room dimensions are width 1.5 foot lentgh, 2,5 foot, and 2 foot high this space is smaller than i was quoting for. The fan wasnt up to the job but the one i installed works lovly nice air flow loads of natural co2 to the plants the whole veg room works a treat. There are 2 settings on the fan and as its 5 " in diamiter you are getting the volume of air passing throutgh.

I do not use a intake fan as she is powerfull enoutgh. I have enclosed a few pics its not a stelth room as its located underground but the idea will work for a stelth box.

The noise can very easly be sorted out just wrap the fan in some rockwall then cover with mylar and they arnt noisy at all to start with bro. You would not here it at all.

Grow it Green not mean

The pics are in my gallery

 

In my experience I like to go with numbers... I like knowing the air flow, that way I can more accurately control air flow and temperature

P.S. That fan might not be overkill, it depends on it's CFM rating... Just with a name like "high pressure inline".... That makes me think it's probably a higher CFM

 

Get a CPU duct... it's used to channel air from the out side of a computer case straight on to the CPU or other components... sometimes the northbridge

But then once you have that duct, it'll have screws or split pins to attach it to the fan... Then from there just attach normal ducting to it