Active Air Carbon Filter, 8" x 39", 950 CFM

Scrub Strong Grow-Room Odor Before It Leaves the Room, 8" x 39"

Run enough plants under enough light and the air in the room starts to carry, through doorways, hallways, and eventually outside, where neighbors or visitors can pick up on it. Once that smell escapes, there's no calling it back. Active Air's Carbon Filter line is built to catch it first: air pulled through a bed of virgin activated Australian granular carbon gives odor molecules and volatile organic compounds nowhere to go, so what comes out the other side is clean.

This 8" x 39" filter is rated for up to 950 CFM, matched to an 8" exhaust run carrying a heavier odor load than the shorter 8" x 24" model; it ships with a pre-filter and an attached flange so it's ready to mount as soon as it's out of the box.

Key Features & Benefits

• Virgin activated Australian granular carbon — a dense, high-surface-area media chosen for its capacity to trap odor molecules per pound.
• 1.8" carbon bed depth — deep enough to give air real dwell time inside the media instead of rushing straight through it.
• Pre-filter included — screens out dust and loose debris before it ever reaches the carbon, so the bed stays cleaner longer.
• Attached flange, machine-packed housing — connects straight to ducting with no separate adapter, and the consistent pack means predictable performance.
• Powder-coated aluminum tops and bases — lightweight and corrosion-resistant, built to handle daily use in a humid grow room.

Who Should Use This Carbon Filter

This filter line suits growers running active-carbon odor control on their exhaust line, from a single tent pulling a couple hundred CFM up to a multi-light room moving well over a thousand. Match the filter size to your duct diameter and fan CFM so air spends enough time in the carbon bed to scrub effectively.

About Active Air

Active Air is Hydrofarm's equipment line for controlling grow-room conditions, covering fans, ducting, and odor-control filters alongside portable air conditioners and dehumidifiers. The brand has focused on atmospheric-control equipment for indoor growers for more than a decade, with carbon filtration as one of its core categories.

Frequently Asked Questions

How long will this filter actually last?

Active Air rates its carbon filters for up to two years of typical use, though heavy odor loads or dusty rooms can shorten that window. Keeping the pre-filter changed on a regular schedule is the biggest factor in reaching that full lifespan.

Do I still need a separate pre-filter?

One ships already in place and ready to use out of the box, so no separate purchase is needed to get started. Keep a spare on hand so you can swap it in as soon as the original starts looking visibly dirty.

When should I replace the carbon bed itself rather than just the pre-filter?

Replace the pre-filter every few weeks in typical use, sooner in dustier rooms, since it's the cheaper part designed to wear out first. The carbon bed needs replacing once odor starts slipping through despite a clean pre-filter, which signals the media has used up its capacity.

How is the filter mounted to my exhaust line?

It connects directly to ducting through its attached flange, so no separate adapter is needed. Most growers mount it just ahead of the inline fan on the exhaust side, matching the filter's diameter to the duct run.

What's inside the carbon bed?

The bed is packed with virgin activated Australian granular carbon at a 1.8" depth, chosen for its density and surface area. That depth gives air enough time inside the media to trap odor molecules and volatile organic compounds before they pass through.

What sizes and CFM ratings does this filter line cover?

Active Air's carbon filter line runs from a 4" x 14" model rated at 215 CFM up to a 12" x 39" model rated at 1700 CFM. Matching the filter's size and CFM rating to your duct diameter and inline fan keeps air moving through the carbon bed at the rate it's designed for.