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Ventilation|Updated 2025-01-01

Best Inline Fans for Grow Tents 2026 — AC Infinity T4 vs T6 CFM Tested

Quiet 4" and 6" inline duct fans for 2x2, 2x4, 3x3, and 4x4 cannabis grow tents. Real CFM, dB, and smart-control features ranked.

Jump to:#1 AC#2 AC#3 VIVOSUN

Good airflow is critical for cannabis health - it prevents mold, strengthens stems, and works with your carbon filter to control odor. We tested the top inline fans to find the best for home grows.

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At-a-glance comparison

Skip the long write-ups — pick the column that matches your needs and click through.

 
#1Editor's Choice
AC Infinity CLOUDLINE T4
Best Overall for Home Grows
#2Best for 4x4
AC Infinity CLOUDLINE T6
Best for Larger Tents
#3Budget Pick
VIVOSUN 4" Inline Fan
Best Budget Option
Price$109.99$159.99$29.99
Rating★ 4.8★ 4.8★ 4.4
Size4 inch6 inch4 inch
CFM205 CFM max402 CFM max190 CFM
Noise25 dB at low32 dB at low45 dB
ControlDigital thermostatDigital + BluetoothOn/off
Power30W40W25W
Best for2x2 to 3x3 tents or supplemental 4x4 ventilation4x4 tents and larger growsBudget-conscious beginners
BuyBuy →Buy →Buy →
#1Editor's Choice

AC Infinity CLOUDLINE T4

Best Overall for Home Grows

$109.99
(4.8)
AC Infinity CLOUDLINE T4

Our Verdict

The gold standard for grow tent ventilation. Whisper quiet, smart controller, and perfect for 2x4 or smaller tents. Set it and forget it.

Best For: 2x2 to 3x3 tents or supplemental 4x4 ventilation
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Pros

  • +Whisper quiet operation
  • +Temperature/humidity automation
  • +PWM speed control
  • +Mixed-flow design
  • +Excellent build quality

Cons

  • -Premium price
  • -Controller could be simpler
  • -4" may be small for 4x4+

Key Specifications

Size4 inch
CFM205 CFM max
Noise25 dB at low
ControlDigital thermostat
Power30W
#2Best for 4x4

AC Infinity CLOUDLINE T6

Best for Larger Tents

$159.99
(4.8)
AC Infinity CLOUDLINE T6

Our Verdict

Same quality as the T4 but sized for bigger grows. The 6" fan handles 4x4 tents easily and has headroom for expansion.

Best For: 4x4 tents and larger grows
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Pros

  • +Handles larger spaces
  • +App control available
  • +Very quiet for its power
  • +Same great controller
  • +Future-proof choice

Cons

  • -Higher price
  • -Overkill for small tents
  • -Larger footprint

Key Specifications

Size6 inch
CFM402 CFM max
Noise32 dB at low
ControlDigital + Bluetooth
Power40W
#3Budget Pick

VIVOSUN 4" Inline Fan

Best Budget Option

$29.99
(4.4)
VIVOSUN 4" Inline Fan

Our Verdict

A solid budget choice that gets the job done. Louder than AC Infinity but effective. Good starter fan if budget is tight.

Best For: Budget-conscious beginners
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Pros

  • +Very affordable
  • +Reliable performance
  • +Easy installation
  • +Good airflow
  • +Simple operation

Cons

  • -Noticeable noise
  • -No speed control (without addon)
  • -Basic construction

Key Specifications

Size4 inch
CFM190 CFM
Noise45 dB
ControlOn/off
Power25W

Inline Fan Buying Guide

Sizing Your Fan

Calculate tent volume (LxWxH in cubic feet). Your fan should exchange that volume at least once per minute. For a 2x4x5 tent (40 cu ft), a 200 CFM fan is plenty with room for carbon filter restriction.

Why AC Infinity Dominates

Mixed-flow fan design is quieter and more efficient than old axial fans. The smart controller automates temperature/humidity. It's worth the premium for the silence alone.

Carbon Filter Compatibility

Your carbon filter reduces effective CFM by 20-30%. If your filter is rated for 200 CFM, pair it with a 200+ CFM fan to ensure adequate airflow.

Frequently Asked Questions

Do I need an intake fan too?
For most home tents, no. Passive intake (just open the lower vent flaps) works fine — and negative-pressure setups (exhaust-only with the AC Infinity T4 or T6 in this list) actually help with odor control by routing all incoming air through your carbon filter. The smart controller on AC Infinity fans even adjusts speed automatically based on temp/humidity.
How loud is a grow tent fan?
Budget fans like the VIVOSUN 4-inch run 40-50 dB on max — noticeable in a quiet room. The AC Infinity CLOUDLINE T4 in this list runs 25 dB on its lowest speed (barely audible) thanks to the EC motor and rubber-mounted blades. If your tent is in a bedroom or living space, it's the difference between hearing your grow and forgetting it's there.
Can I run my fan 24/7?
Yes, and you should. Constant airflow prevents mold (especially in flower) and keeps the carbon filter actively scrubbing. AC Infinity fans are explicitly rated for continuous operation; the smart controller will modulate speed based on temp/humidity targets so you're not running max airflow at night when temps drop.

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