Each nozzle uses roughly 1 gallon of water per hour. The total amount of water used per hour is roughly equal to the number of nozzles in the entire system.
When looking at Pump Module or Fan Pump Unit specifications, the pump GPM is not the absolute and constant output, it is merely the maximum output that the pump is able to handle. In other words, the pump can output less GPM than stated when the total number of nozzles attached is less than the maximum allowed for that pump.
For example: A 0.5 GPM Pump Fan Unit with 8 nozzles (HMI-2405-8) will use around 8–10 gallons of water per hour, not 30 (the pump output is a maximum of 30 GPH.) Using the same pump with satellites for a total of 20 nozzles on all fans will use around 20–25 gallons of water per hour. If more nozzles are needed to cool a very large area, a bigger pump capacity (such as 1.0 GPM) will be required -or- another system has to be created with another pump.
Unless otherwise instructed by a properly trained HydroMist representative, do not attach multiple pumps into the same connected system.