Monitoring salinity is crucial for the health of aquarium inhabitants. SALINITY MODULE-PM2 allows users to track salinity levels with the help of their Apex system and receive notifications when parameters are out of the safety zone. There's also an additional temperature port and 6 I/O switch inputs for ATO, feed buttons, or leak alarms. When used, this extra temperature port is coupled with the conductivity probe's value and produces a more precise, real-time salinity reading.