Neptune Apex ORP / Redox Electrode Double Junction Probe

The probe measures ORP in your aquarium with an Apex System or a PM1 module. You can replace a worn out ORP probe (its recommended to replace your Lab Grade ORP probe every 18-24 months). This probe can be used when you are adding another tank to your system, want to measure ORP in it, and purchased a PM1 to do so.

Lab Grade Probes tend to last longer, give more accurate results, stay calibrated longer, and need replacing less frequently.