Quick answer
A grow tent setup has six parts: tent, light, exhaust fan with carbon filter, circulating fan, timer, and growing medium. Match the light to floor area. Match the fan to tent volume. Seal light leaks before you start flowering.
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Tent size and height
Pick the tent by plant count and room. Common sizes and floor area:
How to Install a Carbon Filter in Your Grow Tent
- 2x2 ft: 4 sq ft, 1 to 2 plants
- 2x4 ft: 8 sq ft, 2 to 4 plants
- 4x4 ft: 16 sq ft, 4 to 6 plants
- 5x5 ft: 25 sq ft, 6 to 9 plants
- 4x8 ft: 32 sq ft, 8 to 12 plants
Height matters more than width for tall sativas. A 4x4 tent at 80 in tall leaves about 60 in of usable plant height after the light, the carbon filter, and 12 to 18 in of space between the fixture and the canopy. Leave 24 in of clearance on all sides for ducting, cords, and access.
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Light
Estimate LED power by floor area. Use 30 to 40 watts per square foot at the wall for flowering and 15 to 25 watts per square foot for vegetative growth. A 4x4 tent covers 16 sq ft, so it needs 480 to 640 W in flower. A 2x2 tent needs 120 to 160 W. LED fixtures rated 2.5 to 3.0 micromoles per joule (umol/J) hit these numbers with less heat than HID lamps.
Set 18 hours on and 6 hours off for photoperiod plants in veg. Switch to 12/12 for flower. Autoflowers run on 18/6 or 20/4 for the full cycle.
Airflow and odor
Size the exhaust fan on tent volume. Multiply length x width x height in feet to get cubic feet, then exchange that air every 1 to 3 minutes.
Example: 4 x 4 x 6.7 ft = 107 cu ft. One exchange per minute equals 107 CFM.
Add margin. A carbon filter cuts airflow 20 to 25 percent. Bends, a long duct run, and a passive intake add more restriction. Multiply the base CFM by 1.5. That 4x4 tent lands at 150 to 200 CFM. Use 4 in duct for tents up to 8 sq ft and 6 in duct for 16 sq ft and larger.
Mount the carbon filter inside the tent near the ceiling. Run duct from the filter to the fan to the exhaust port. Passive intake vents must total at least twice the area of the exhaust duct. A 6 in duct is about 28 sq in, so vents need about 56 sq in of open area.
Add one 6 in to 8 in oscillating clip fan per 4 sq ft. Aim it above the canopy, at the tent wall, so leaves move in a light flutter. Constant airflow on one cola causes wind burn.
Environment targets
- Temperature, lights on: 70 to 80 F
- Temperature, lights off: 65 to 70 F
- Relative humidity, veg: 60 to 70 percent
- Relative humidity, flower: 40 to 50 percent
- Dark period in flower: 12 hours with no light gaps
Humidity above 60 percent in late flower raises the risk of bud rot. Run a dehumidifier in the room, not inside the tent.
Medium and pots
Soil in 5 to 7 gallon fabric pots suits most 4x4 tents. Coco coir with perlite works in 3 to 5 gallon pots and needs water each day. Fabric pots air prune roots and dry faster than plastic. Plan a drain tray and a wet vacuum or a low profile drain pan.
Electrical safety
A 480 W light, a 50 W exhaust fan, and a small clip fan draw about 550 W. At 120 V that is 4.6 amps. A 15 A circuit holds 1,440 W at 80 percent of its rating, so one tent fits with room for a dehumidifier. Use a GFCI outlet. Do not chain more than one power strip. Keep cords off the tent floor.
Setup order
- Build the frame on the floor, then lift it and fit the cover.
- Set the tent on a level surface. Level the floor if the tent rocks.
- Hang the carbon filter and the exhaust fan. Run duct to the exhaust port.
- Hang the light at the top of the tent. Move a detachable driver outside.
- Run cords through the top ports. Seal unused ports.
- Install the intake vent cover and a filter sock if the room is dusty.
- Add the clip fan, timer, and thermometer/hygrometer.
- Zip the tent. Check for light leaks in a dark room with the light on inside.
- Run the system empty for 24 hours. Record temperature and humidity highs and lows.
Cost
US prices, 2024 to 2025: a 2x2 kit runs $150 to $300. A 4x4 kit with a 480 W LED runs $400 to $900. A carbon filter costs $60 to $150. A 6 in inline fan costs $80 to $180. A 4x4 tent alone runs $100 to $200.
Common mistakes
- Fan too small for tent volume plus filter loss
- Light leaks at zippers and port covers during the dark period
- Humidity held above 60 percent in late flower
- No intake area, which makes tent walls suck in and stalls the fan
- One circuit loaded with a light, a heater, a dehumidifier, and a fan