Usually used with aquarium accessories like RODI inputs, calcium reactor feed lines etc., this Neptune Systems flow sensor can be placed in line with the flow on 1/4″ tubing, connected to the Neptune Systems FMM, and communicate to your Apex the flow rate of water through that pipe. The flow sensor itself uses push-fit connectors to make connecting to your system as simple as possible. The FS-25 will work with flow rates from 3-12 gph.