Air Movement

Emporium Hydroponics • October 29, 2025

The Science that will Go with the Flow

A plendid grow tent to use with intelligent air conditioning that can be controlled from your smartphone

Proper air movement is critical for a successful hydroponic grow room. It affects plant health, disease prevention, CO₂ availability, temperature control, and humidity levels.


Here's how to set up air movement the right way...


1. Understand Why Air Movement Matters


  • Prevents mould/mildew: Stops stagnant, humid air.
  • Strengthens stems: Mimics outdoor breeze, promotes stronger plant structure.
  • Even temperature & humidity: Distributes heat from grow lights and keeps humidity uniform.
  • Improves CO₂ uptake... Fresh air = better photosynthesis.


2. Equipment You’ll Need


Oscillating Fans


This will create constant gentle air movement across plants. The best placement for the fans is...

:

  • 1–2 fans at canopy level, oscillating back and forth.
  • Angle slightly downward but never blowing directly on plants at high speed.


Exhaust Fan (Inline Fan)


  • Purpose: Pull stale, humid, or hot air out of the grow room.
  • Size: Depends on grow room volume (see CFM calculation below).
  • Placement: High on the wall or ceiling (because heat rises).


Intake Fan or Passive Intake


  • Purpose: Bring fresh air into the room.
  • Passive intake: Just an open vent (relies on negative pressure from the exhaust).
  • Active intake: Small fan pulling air in (ideal if passive isn’t sufficient).


Environmental Controllers (optional but ideal)


  • Temp & humidity controller to turn fans on/off based on set levels.
  • Can also control humidifiers/dehumidifiers and heaters.


3. Calculate Fan Size (CFM)


CFM = Cubic Feet per Minute — how much air your fan can move. The formula is below:


  • Room volume (ft³) = Length × Width × Height
  • CFM needed = Room volume × Air exchange rate (typically 1 every 1–3 minutes)


An example is below...

  • Room size: 10' x 8' x 7' = 560 ft³
  • Desired exchange every 2 minutes: 560 ÷ 2 = 280 CFM


For this scenario, choose an exhaust fan rated at least 280 CFM (add 10–20% buffer if using carbon filters or ducting).


4. Control Temperature & Humidity


  • Temp Range: 70–80°F (21–27°C) lights on, 65–75°F (18–24°C) lights off
  • Humidity (RH):
  • Seedlings: 65–70%
  • Veg: 50–70%
  • Flowering: 40–50% (lower to prevent mould)


Optional Tools...


  • Humidifier/Dehumidifier (based on your climate)
  • AC or Heater for temp control
  • CO₂ supplement (optional, if you're sealing the room)


5. Set Up Ideal Air Flow Pattern


[Passive/Intake Vent] ---> [Canopy + Oscillating Fans] ---> [Exhaust Fan]


  • Fresh air enters low (intake)
  • Moves across plants with help of oscillating fans
  • Exits high via exhaust fan
  • Creates a clean airflow loop


6. Monitor and Adjust


Use digital thermometer/hygrometer combos placed at:


  • Canopy level (main concern)
  • Room corners or near air vents (check for dead spots)


Common Mistakes to Avoid


❌ No air circulation: Leads to hot/humid pockets = mold & weak plants.

❌ Too strong airflow: Can wind-burn leaves and stress plants.

❌ No exhaust: Just recirculating hot, stale air.


Would you like any further knowledge or advice on this? If so then please feel free to give us a call or visit us in store!