Carbon Filter - Limiting Airflow, but by how much???

Hello All:

My room is 12x8x8 (768 ft^3). I used the rule of thumb that the air should be replaced every 5 minutes to choose an exhaust fan, and as a result I got an 4" 177 cfm inline fan. What I failed to consider in the fancy calculation is that I have a carbon filter through which the air is being pulled, and I'm sure this inhibits the air flow. My question is, does anyone happen to know about how much does the filter impede airflow (IE - What would the effective cfm's of my 177 cfm fan be with the carbon filter connected?) I'm starting to think I screwed the pooch and I might need to upgrade to the 6" higher cfm fan now. Any info you have would be most helpful. Thanks.

with a 4" inline it will be about 100% they just don't have any power. you need a cage fan and depending on the filter it will need to be strong.

different carbon filter designs will reduce cfm by different amounts due to surface area and thickness of the carbon.

is it a diy filter or a premade one? if it's a premade one, post what it is and maybe someone with the same one can chime in with more info. if it's a diy one..then i dunno..maybe run some tests on yer own...like off the top of my head (im pretty high) maybe you could take a huge garbage bag and put it over yer exhaust to see how quickly it fills with air (time it) with and without the filter...do a lil math and you should be able to at least make an accurate guess on how much it is reducing airflow...also you could do the reverse..like fill the bag up then put it over your intake to see how quickly it deflates, but really only if you have single intake and your room is well sealed...yeh actually taking the reading off the exhaust would be WAY more accurate. hope this helps a lil bit.