Please check my numbers before i buy first fan!

I know this thread was started multiple days ago but I felt I should throw in my .02 cents worth.
Last summer was my first grow. My space is 12.25 sf. I started with a fan that did not deliver what it was supposed as far as air flow. I replaced it with a 4" fan that was supposed to deliver 400 cfm. This still did not provide enough flow. I had to run it wide open and it still could not handle the heat or the odor even after turning my ballast down to 250w.
Point is, I would tell anyone I liked to START with a 6" fan since you can slow it down if it working too well.
Hope this helps.


Hi @Tarzan
Yeah that does help!
I’ve got a small tent but have got a 900w viparspectra so I’m sure I’m gonna have a lot of heat to get rid of!
Was looking at 4" fans but am now gona go for a 6"

Make sure you get a fan speed controller too bro your led won’t generate nearly as much heat as his hps fixture
I run one 1000 watt & two 400 watt cob light in my tent 4x4x7 and my temps maintain around 80 in tent with 72 degrees outside tent I run a 4 inch exhaust with carbon filter at 100 cfm with no problem with maintaining temps and I recycle my tent air
in a week or so when out door temps get warmer I’ll turn on their exhaust in my room to keep temps in check but will still maintain 70 degrees in grow room
I exhaust room directly out side of house

I.m glad to be of any help!! I think you will be happy with the 6". My room
is 3.5’ x 3.5’ and I was disappointed in both of the 4" fans I tried. I am
confident my new 6" fan will do the trick. Good Luck! Happy growing!!