RDO Blue uses In-Situ’s patented Optical Rugged Dissolved Oxygen technology, an EPA-approved dissolved oxygen measurement method ideal for measuring DO and temperature in even the harshest environments. Suitable for handheld use or long-term deployment in fresh water or saltwater, this low-maintenance dissolved oxygen probe offers robust performance at a lower cost than other DO meters.

RDO Blue requires no calibration or conditioning prior to deployment and doesn’t use membranes. The replaceable RDO Smart Sensor Cap stores calibration coefficients for automatic, error-free setup. And a unique, three-layer system provides unmatched chemical and abrasion resistance.

Use included Modbus/RS485 communication protocol to easily integrate with PLC systems or telemetry with HydroVu data services for real-time feedback and process control.


Patented RDO® Technology

EPA-approved optical RDO method makes Dissolved Oxygen sensors easy to use, with a multilayer, abrasion-resistant formulation, a smart cap that carries calibration onboard, and instant hydration to eliminate the need for conditioning prior to use.

Smart Sensor Cap

RDO sensing foils are calibrated at 90 discrete points, and the coefficients are stored in the replaceable cap. Simply press it on and you’re ready to go, no data entry or extra steps needed.

Abrasion Resistance

A unique, three-layer system provides unmatched chemical and abrasion resistance, extending the life of the sensor cap and expanding the range of compatible conditions.

Instant Hydration Conditioning

Unlike other DO sensors, the RDO formulation doesn’t require 12-24 hours of hydration conditioning and reads accurately within 90 seconds of going from dry to wet conditions.

Smart Addressing

All RDO instruments have an easy-to-configure Modbus interface, so they’re ready for integration into another system and access to data is reliable.

Enhanced Reliability

Ryton construction and complete internal potting to create a solid core provide strength and chemical resistance to eliminate most common failures.


0103000 RDO Air-Blast Guard for active clearing of the sensor tip with air or water blast

0101540 RDO Calibration Kit for performing optional 1-point or 2-point user calibrations

0103010 RDO Antifouling Guard will copper coil to limit biological growth around the sensor tip

0102930 RDO Standard Guard Replacement Kit to replace a lost or damaged Ryton Guard (included with all new RDO Blue instruments)

0102940 Weighted Guard to provide additional weight for use in areas with high flow or vigorous mixing

0088720 RDO-X Sensor Cap Replacement Kit with recommended reading life of 2 years (included with all new RDO Blue instruments)

0077700 RDO Fast Sensor Cap Replacement Kit with recommended reading life of 1 year)