4 inch fan for 6 inch filter

herbs1

Well-Known Member
I have a 4 inch inline fan (190 cfm) and a VenTech carbon filter. I haven't used the filter yet, but read mix reviews on this it. Im thinking of buying a phresh just in case this one doesn't work out if I grow. Can I buy a 6 inch phresh and use a 4x6 ducting reducer to make the fan work in this filter?
 

Kevin the Great

Well-Known Member
I have a 4 inch inline fan (190 cfm) and a VenTech carbon filter. I haven't used the filter yet, but read mix reviews on this it. Im thinking of buying a phresh just in case this one doesn't work out if I grow. Can I buy a 6 inch phresh and use a 4x6 ducting reducer to make the fan work in this filter?
Yes. Actually works better that way.
 

HarveyHarvester

Well-Known Member
Sounds like I have the same fan and filter (VenTech) and am not very pleased with the filter but since you are running it with the smaller 4" fan you may not have any problems. As others have said, that is actually better, the larger filter is rated at a higher cfm than the fan so the odor has more/longer contact with the carbon.
Am really pleased with the VenTech inline fans tho, have 2 of the 4" and 2 of the 6". no complaints with the fans.
 

herbs1

Well-Known Member
The 4 inch works great and when I hook up the carbon filter, its super quiet too which is nice.
 

HarveyHarvester

Well-Known Member
yep, like a muffler.
It also helps to have a basic understanding of how those filters work...

The filters use "adsorption" to contain the odors, unlike "absorbtion", in which the material absorbs something and gets larger; adsorption simply stores the material and gets heavier instead of larger.

This is oversimplified:
a odor particle comes thru the filter and falls into a "hole" where it is trapped and cannot escape. it still smells bad, it's just stored in the filter.
Once the filter has become saturated and all the holes are filled, a odor particle comes thru that is heavier than an existing/stored odor, the lighter odor is released and replaced by the heavier odor. that is why we get the occasional whif-o-weed.
 
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