After measuring and determining if flow rate is higher or lower than needed our team will recommend slowing the fan down and creating a correction factor based on actual versus displayed volume. If slowing the fan down is out of the question and the motor powering it is below F.L.A (Full Load Amperage) our team typically recommends resheaving. This of course depends on many variables what the fan is servicing, fan capacity, cleanliness of the system etc.