I think I just need an exhaust fan rather than this 105CFM incline fan to pull air from out of my grow tent. Can you guys suggests any quiet exhaust blowers around 150CFM? Any thing that has a DBA around 30 were be awesome.
Hey shinto, the inline fan you have is acting as your exhaust fan. Don't let the terminology slip you up.
...in-line fans are fans that usually fit in-line with duct system (hence the name "in-line.") An exhaust fan is any fan that exhaust air, odors, particulates, etc. An in-line exhaust is a fan that happens to fit in-line that is also exhausting ventilation.
When you're looking at your carbon scrubber; there's a few things to keep in mind:
Viagrow 4 in. Carbon Air Filter 2 with Flange 55-110 CFM Exhaust
See the 55-110 CFM part? That is the recommended air flow and max recommended air flow. The air flow rating is the rating set by the manufacturer of the carbon filter for optimal adsorption on the activated carbon, based on the type of activated carbon and the size/shape/design of the filter.
Exceeding the maximum rating is not recommended; the adsorption process by activated carbon takes a certain amount of contact time to be effective. If you exceed the rating by too much; air and odor causing molecules are being push through too fast and will not have time to be adsorbed (causing smell to exhaust.)
If your air flow rate is marginally less than the rating of the scrubber; the scrubber will not effectively be able to pull the air and odor causing molecules through the activated carbon, making it much less effective and potentially causing the fan to work harder, which generates heat and shortens the life of the fan. A fan that is working harder tends to generate more noise too.
This is your fan you listed:
VENTS 105 CFM Power 4 in. Mixed Flow In-Line Duct Fan
Carbon scrubbers come in all different shapes and sizes and designs depending on the manufacturer. Because of this, they all exhibit different pressure drops based on their design and the types of fan being used with them.
From what I've read, there's around a 15-20% CFM reduction loss on the output of the fan because of the pressure loss caused by the filter (note, this is a ball park figure.)
For sake of argument, let's say we factor in a 15% loss from the scrubber:
105 CFM * .15 = 15.75 CFM loss
With the drop, you're looking at around 95 CFM. If you are venting it out of the tent, there can be additional drops depending on the length of duct, size of duct, number of bends and turns (each 90 degree turn can cause up to nearly 4% CFM loss.)
If you're comfortable posting them up; a few pictures of your setup and how you have your carbon scrubber/fan setup would be very beneficial to making a good recommendation.
Also, most importantly; are you noticing any smell? What is your primary concern; whether the scrubber is operating efficiently/effectively or whether or not you are achieving negative air pressure?
Do you have any active air intakes?
