Start Measuring Salinity in Your Reef Replace an old probe or add salinity monitoring to your Apex Aquarium Controller. Maintaining consistent salinity in your aquarium is key to the well-being of every organism inside it. Often, we're so busy that we overlook changes in the salinity of our reef aquarium until problems arise. With real-time salinity monitoring, you can be alerted to potential issues and do something about it. No Salinity Port? No Problem! If your Apex doesn't have a salinity probe port, you can easily add one with the separately available PM2 Salinity Module. The PM2 Features a salinity probe port, temperature probe port, and an I/O port. Use the Right Calibration Solution (sold separately) For Saltwater: 53000 µS Conductivity Solution For Freshwater: 447 µS Conductivity Solution What's Included? 1x Neptune Systems Conductivity Probe