The Neptune Systems pH/ORP/Redox Probe Module – PM1 is probe module for use with a pH or ORP/Redox probe. Also suitable to an I/O breakout box. The PM1 probe module is just what you need if you want to monitor pH or ORP in your tank. The module comes with an extra temperature port as well as six I/O switch inputs for use on ATO, feed buttons, etc. This module is perfect for someone that wants to add an additional pH or ORP port to their Apex System.
Having an extra temperature port and probe is always useful. Some people like to put one probe in the display tank and one in the sump just for redundancy. That way, should your return pump go out, you would be monitoring the display tank and would see the temperature falling and know something was not right. With the PM1 you can easily use your existing Apex to monitor additional tanks simply by adding this module.