S-Vents TT 100 4" extractor or in line fan

Vents TT inline Fan 100mm 145-187m3/h
Manufactured from plastic, the Vents TT Range is ideal for installation in ventilation systems with high pressure, strong airflow, and low noise level.

Features:
Quiet and safe operation
Compact size
Speed switch
Access to motor and impeller without dismantling ducts
comes with wall mountable bracket
fan is removable from its bracket via 2 simple clips
can be wired to 2 seperate speeds
145-187m3/h

What size fan do i need?
Measure the Height, Length and Width (in metres) of the growing environment.
Multiply together (H x L x W) to give the cubic meter volume.
Multiply this figure by 20.
This is the size of fan required to change the air 20 times in an hour.
Buy the fan slightly above the figure calculated if possible to ensure adequate ventilation..