Active Air Inline Carbon Filter - 6" x 24"

A terminal filter is closed at one end and must be placed at the terminus of the duct run — typically inside the grow room. An inline filter like this one is open at both ends and connects mid-duct, meaning it can be installed anywhere along the duct line. This allows you to mount the filter outside the grow room entirely, running a duct extension into the space to extract air, which is a significant advantage when interior space is limited.

In a single-stage filter, air makes one pass through the carbon bed, and any odor molecules that aren't captured on that pass exit untreated. Two-stage filtration routes air through the carbon bed twice — on entry and exit — effectively doubling the contact opportunity between odor molecules and the activated carbon surface. This results in more complete VOC adsorption, particularly at higher airflow rates where dwell time in the carbon bed is shorter.

Yes — that's one of the primary advantages of inline filter design. Mount the filter in an adjacent space, attic, closet, or above the tent, then run a length of ducting from the filter into the grow area. The fan can also be positioned outside the room if desired, keeping both the filter and fan out of your grow space completely and maximizing usable interior square footage.

No — the two-stage internal design is bidirectional by nature, so filtration effectiveness is the same regardless of which end air enters from. This simplifies installation since you don't need to check or mark airflow direction before connecting your ducting, which is particularly useful in tight spaces where rotating a heavy filter is inconvenient.

The Active Air 6" × 16" Carbon Filter is a terminal design rated at 400 CFM — it mounts at the end of a duct line, typically inside the grow room, and draws air through an exterior mesh. This inline model offers 500 CFM, two-stage filtration, and mid-duct placement flexibility. If interior space is tight or you want the filter and fan located outside the room, the inline model is the better choice.

Pair this filter with a 6" inline fan rated at or below 500 CFM for optimal odor control. Running a fan that exceeds the filter's rated airflow reduces dwell time in the carbon bed and allows odor molecules to pass through before being fully adsorbed. A variable-speed fan gives you the flexibility to dial back airflow during peak odor periods for more thorough filtration when it matters most.