ORP Meter

The ORP Meter measures the oxidation-reduction potential of aquarium water in millivolts (mV), providing a single composite indicator of the water's overall oxidative or reductive state. ORP reflects the balance between oxidising substances such as ozone, dissolved oxygen, and chlorine, and reducing agents such as organic waste and ammonia.

In reef aquariums, ORP is used to monitor ozone dosing, where a target of 350–400 mV correlates with excellent water clarity and low dissolved organic carbon. In freshwater systems, ORP above 200 mV indicates healthy oxidative conditions, while values dropping below 150 mV suggest organic overload or poor filtration.

The meter uses a platinum-tipped combination ORP electrode connected via BNC connector. Response time is 30–90 seconds depending on water chemistry. Most ORP meters are also compatible with automated controllers for ozone dosing regulation.