The PM1 probe module is just what you need if you want to monitor pH or ORP in your tank. And, there is an added bonus, you get an extra temperature port as well as six I/O switch inputs for use on ATO, feed buttons, leak alarms or whatever else you may come up with. This module is perfect for someone that wants to add an additional pH or ORP port to their Apex System. Great uses for the extra ports If this is an additional pH port, it could be used for another tank or for control of the CO2 solenoid on your calcium reactor. If you choose to use it for ORP, you could have the Apex use that ORP value to turn on and off an ozone generator. Of course, you could set up audible or email alerts too if these values should fall out of range. Extra Temperature port 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. Want to monitor an additional tank? With the PM1 you can easily use your existing Apex to monitor additional tanks simply buy adding this module. Then, just buy our pH and Temperature probes and you’ll be all set! Six I/O Switch Ports Purchase a I/O Breakout Box and you can monitor the off/on state of six I/O signals. This is useful if you want to set up an ATO (Auto Top Off), a feed button, or even a sump door alarm or light switch.