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Size of fan and carbon filter (55 cm x 55 cm x 120 cm)

Hi guys. I need some help so I have a couple of questions.

I’m going to build a small grow room (scrog) 55 cm x 55 cm x 120 cm (height).


This is the calculations I did for the fan:


55 cm x 55 cm x 120 cm = 1.80 x 1.80 x 3,93 (feet) x 3-4 =  38,19 -  50,93 CFM = 86 m3/hour

I guess my fan needs to have a higher cm/m/hour than that.


I have been looking at this fan:


I am going to be using a variac speed controller. I think I want to use the fan at 40 % of its max speed, in order to make it more quiet.

http://www.onestopgrowshop.co.uk/fans-filters-and-air-control/duct-fans/systemair-rvk-5-inch-125mm-l1-in-line-duct-fan-341m3-hr.html : 323m3/h or 190 cfm. 40 % speed = 129 m3/h or 76 cfm.

I have also been looking at the Ruck (can fan) and rhino fan.


My first questions is, how powerful should my fan be for this grow room? Is this okay: 129 m3/h or 76 cfm?  How much higher can a fans m3/h/CFM rating be than what the grow room needs as a minimum?

My grow room is not that big, but I think I would be able to fit that fan inside of the grow room. I am going to put it in a box like this: https://www.icmag.com/ic/showthread.php?t=229614 (of course not as big) and then use oversized insulated ducting.

The lights I’m going to use will be something like this: http://timbergrowlights.com/200-watt-cree-cxb3590-4-cob-grow-light-kit/ (DIY by following a guide)


What size of carbon filter should I use for this grow room? My grow room is not that big, so I hope I will be able to fit everything in it. Should the carbon filters cfm/m3/hr rating be higher or lower than the fans cfm/m3/hr rating?


I hope you are able to understand my English J


Stiggy123, Denmark

Edited by stiggy123

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I think you will get away with a 4inch fan and filter in there if using cobs. 5inch fan and filter in that space is going to take up a lot of room. I've always used mountain air, but they are fairly large. Rhino do a smaller 4inch.  I grow in a cab that's 60cmx95x200 and use a 4 inch with passive intakes. 


Yea, you want your filter to be rated at a higher cfm rating as otherwise the fan can pull air through it faster than its scrubbed. With your step controller though shouldn't be an issue. Good luck :) 



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Okay. It seems like the 4 inch RVK and 5 Inch RvK fan have the same dimensions. 



I have been thinking about using a 5 inch fan (at 40 %) and a duct reducer so i can connect a 4 inch filter to the fan. If that is possible..


Thanks :) 

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get the 5" filter to match the 5" fans dimensions.

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