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Extractor fan size

Martins G

New Member
I have 120cmx120cmx200cm grow tent, how big extractor fan do i need?
Now i have 125mm cooltube with old 120mm extractor fan (20w; 200m3/h) but its too noisy and theres abit heating problem so i want a new system.
So question is how much m3/h fan do i need for optimal air flow?

Bulbs are 400w metal halide during veg and planned 600w dual spectrum hps for flower.


New Member
need more info or pics to see what you are really doing. if you are in a 120x120 tent and your are running a cool shade .then you coolshade fan should be taking most of the heat away.pursuming you have it venting out the tent, are you running a carbon filter on it own fan as well,if you are then you wont have problems.unless the van that takes the heat away from your cool shade is not working properly.if you are not running a carbon filter and its own fan.then you will need a 150ml fan and 150ml dutching to take the heat away from tent.. not enough info in your question.................................................. what temp are you at with lights on?
are you doing negative pressure?
have you got a carbon filter?
what size are they.


New Member
Your room is 1.2m x 1.2m x 2m, so the volume of the room is 2.88m^3. You want a fan that will dump all the air in your room and bring in new air all within a minute or two, so ideally you want something that will extract 2.88m^3 of air per minute, or 173m^3/hour. Then adjust for ducting and possibly a carbon filter, you will want something around 250-300m^3/hour for your tent. Bigger fans running on lower settings make less noise btw, bigger is better if you can make it work

Martins G

New Member

Heres photo :D
I have no carbon at all (no any smell yet) but soon i will look for one. So looks like i should look for some 280m/3 one.

Found that mine FAN has 50db, will there be any difference with this one for example Air extraction TT Kit - Extractor / Filter / Flexible Tube 280 m³/h (125mm) | eBay ?
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