Each fan has a rating that tells you how many cubic
feet of air per minute (CFM) it will move. When dealing
with above average temperatures you will want your fan
to exchange the grow room air 3-5 times in one minute,
so for a room that is 40 cubic feet, a fan that is
capable of moving 120-200 cfm (cubic feet per minute)
is recommended. If you only want to replace depleted
levels of CO2 and are growing in a closet using
fluorescents, one room change per five minutrients
(divide room size by 5) will be adequate.
To calculate your room size, multiply Width by Length
by Height, this will give you the CFM rating required
for one room change per minute.
Air that's exhausted will be replaced by fresh air,
which is drawn from
Passive Intakes-
located opposite the exhaust at the floor of your
grow room (Recommended for closet grows) or
forced in using another blower (recommended for
larger grow rooms).
For internal circulation oscillating fans are In my
opinion the most efficient contraptions for circulating air
in a room. The gentle back and forth sway of the fan is
very beneficial for the developing plants. These fans
tend to keep anaerobic moulds down by constantly
freshening any potentially stagnant air. Home
improvement centres carry a large array of various
types and styles of air-moving fans, there are
wall-mounted styles available and most are relatively
inexpensive.
NOTE: To convert CFM to CMH use the folowing
formula CFM X 0.03 X 60 = CMH
To help maintain a lower room temperature follow this
link detailing how to construct a
DIY- Air-cooled
Reflector
