The mV monitor is a precision instrument for continuous monitoring of the Redox (ORP) value in marine aquaria. The Redox potential is an electric value that is a parameter for the purity of the water. The LED display continuously shows the current Redox (ORP) value of the aquarium water. The ideal value is between 300-450mV and can be raised to the required level with ozone. Conversely, the ideal Redox potential of a denitrification filter is between -300 and -100mV, which can be monitored so that water flow through the filter can be adjusted to maintain the required level. The measuring range covers mV values from -1,999 to +1,999 mV. The electrode is connected to the mV monitor via a standard BNC connection. Included in the package: mV monitor, mV electrode with BNC fitting, Electrode holder, 0-point-plug, Allen key and 12v DC power supply. Optional 230mV solution is available for checking the accuracy of the mV probe.