The Neptune Systems Dissolved Oxygen Module monitors real-time dissolved oxygen levels in your aquarium. Of all the organisms in your aquarium, large fish are at the greatest risk when O2 levels are low. In some situations, a simple malfunction of a skimmer can lower O2 levels enough to harm your fish. This is where the PM3 Dissolved Oxygen module provides assistance.

If O2 levels approach the danger zone, the Apex can immediately alert you with an audible alarm or send you an email notification.

While the cost of the PM3 is very reasonable, the downside is that the DO electrode itself is relatively expensive. The DO electrode is a laboratory-grade device and costs about 5 times as much as the PM3 module itself. The good news is that the electrode has replaceable membranes, so you don't have to discard it when it wears out.

• LED Status Indicator
• Contains 2 AquaBus connectors
• Comes with 3′ AquaBus cable
• Galvanic Isolation for accurate and reliable probe readings
• Upgradeable firmware

Other features of the PM3 include 6 digital inputs for float switches, water-on-floor sensors, pressure sensors, etc. The PM3 can provide full data logging support through the Apex Base module.