is my 4 inch fan enough

I have a 4 inch inline fan outside tent sucking thru carbon filter inside tent,is this enough air movement

My wife tells me that 4 inches is.not enough so.i.am.gonna have to.say your fan is probably not.big enough. Joking aside you.are just gonna have to see

Not even close to enough information to give an informed answer. How big is the grow area, what type of lights are you running, what is the temp, how big is the carbon filter, what is the CFM rating of the fan, is it a centrifugal or axial fan?

Yeah. We need grow area dimensions if anything. Never heard of anyone sticking the inline fan on the outside. I'd put your inline fan as close to your filter as possible to get the most suction going.

^ What he said!!

Step 1 – Room Volume
First the volume of the room needs to be calculated. To calculate multiply length x width x height of growing area e.g. A room that is 8' x 8' x 8' will have a volume of 512 cubic feet.

Step 2 – CFM Required
The fan should be able to adequately exchange the air in a grow room once every three minutes. Therefore, 512 cubic feet/3 minutes = 171 cfm. This will be the absolute minimum cfm for exchanging the air in a grow room.

Step 3 – Additional factors
Unfortunately, the minimum cfm needed to ventilate a grow room is never quite that simple. Once the grower has calculated the minimum cfm required for their grow room the following additional factors need to be considered:

1. Number of HID lights – add 5% per air cooled light or 10-15% per non-air cooled light.
2. CO2 – add 5% for rooms with CO2 enrichment
3. Filters – if a carbon filter is to be used with the exhaust system then add 20%
4. Ambient temperature – for hot climates (such as Southern California) add 25%, for hot and humid climates (such as Florida) add up to 40%.

this reminds me that i too need a fan. yes bigger is better. you cant really get it too cool using just a fan. and too much wind speed stresses them out a lil, stunts growth upwards but increases stem thickness (great for holding up those big buds, and low roofs ).

Bigger fans will also run quieter for the same CFM. I've got two 6" fans with a speed controller hooked up to them and have them dialed to about 65% power. My other cab has a 4" fan that's running at 100%. The 4" is louder than the two 6" even though they are pushing more air, even at 65%.

Bah. everyone has 6 inches. I have 12 inches, but I don't use it as a rule


**rimshot**