Carbon filter airflow?

So I've done a decent amount of research and made my own carbon filter. I am kind of confused about how much airflow should be leaving the box. As of now I have two 4" fans (one inlet and one outlet through the carbon filter), should I be able to feel at least some amount of airflow through the carbon filter?, or will there not be a significant amount? I am using pretty fine carbon so I'm thinking that may be the cause. I will also have a Febreze True Air Purifier in the box as well as this carbon filter. There needs to be no smell with this.

if you cant feel any air, then its not right, but hey, thats just my opinion.

That's what I thought too. Should it be prominent airflow?, or just a mouse coughing?

I can only barely feel the air intake on my Phresh 200CFM, and when I say barely I mean BARELY.

But I think that is mainly due to the filter intake being spread over a wide area around the entire can.

My exhaust is powerful and odor control works like a champ, so I assume it is normal. Also, the guys at Greners told me it was normal too.

some times the air is difficult to feel because it is being dispersed over a wider are in comparison to the fans intake or exhaust.
can you flip the fan and pull air through your homemade filter? you should be able to tell if air is moving through it then? if not, maybe to packed your filter to much or something? but if air is being pulled through, and the fan isn't struggling to do so, your probably fine.
you can also test your air flow w/ the flame of a lighter or piece of cat hair, or anything that would move w/ the flow of air. test the movement where u want!

good luck!

wbd said:

I can only barely feel the air intake on my Phresh 200CFM, and when I say barely I mean BARELY.

But I think that is mainly due to the filter intake being spread over a wide area around the entire can.
.

Click to expand...

+1. There's a trade off between velocity and airflow. The best filters have lots of surface area to make it easier on their fan motors .

Thanks for the imput. I'm just going to test it out and see what will work. I also have a Febreze True Air filter inside the box and I will probably get some Ona Gel too just to be safe. Also, should there be more air coming into the box or leaving the box?

As for the lighter test i didn't get really any airflow through the exhaust.

A passive intake should roughly twice the size of the fan exhausting the grow space. So 4in fan roughly 8 in intake hole, 6in then we are up to 12 x 12in circle, hole, openning

pazuzu420 said:

A passive intake should roughly twice the size of the fan exhausting the grow space. So 4in fan roughly 8 in intake hole, 6in then we are up to 12 x 12in circle, hole, openning

Click to expand...

Would that work even with a low airflow exhaust? Or since the exhaust is being expelled slower than the intake would it be alright to keep the same size?