6565FG Flat Glass pH/ORP Sensor

6-Series Legacy Sondes

View YSI 6-Series water quality sondes being used in a variety of water environments for long-term underwater monitoring and spot sampling.

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Simple, accurate pH/ORP measurement in sensors designed for minimal maintenance in sampling, profiling, and long-term monitoring applications.

This sensor must be installed into a 6600EDS V2 sonde to function. Does not function on its own.

  • Overview

    YSI pH and pH/ORP sensors have been carefully designed to perform under all ionic strength conditions, from seawater with a conductivity of 53,000 μS/cm, to "average" freshwater lakes and rivers with conductivities of 200 to 1500 μS/cm, to pure mountain streams with conductivities as low as 15 μS/cm, which has historically been the most difficult medium with respect to accuracy, quick response to pH changes, and minimal flow dependence.

    ORP is determined by measuring the potential of a chemically-inert (platinum) electrode which is immersed in the solution. The sensing electrode potential is read relative to the reference electrode of the pH probe and the value is presented in millivolts.

    6565FG Flat Glass pH/ORP Sensor:
    The YSI 6561FG pH sensor features a 'long-life' sealed gel reference, eliminating the need to refill. Produces unattended pH readings in high-fouling environments on 6600EDS sondes.


    • Wipeable by 6600EDS sonde brush.
    • Glass is well-protected


    • Can produce jumpy readings when touched or near source of static interference
    • Not ideal for lab use.

    Sensor is available for use on the following sonde:

    • 6600EDS V2 only

    General Specifications:
    Range: 0 to 14 units
    Resolution: 0.01 unit
    Accuracy: ±0.2 unit

    U.S. EPA ETV

  • Specifications
    Depth / Pressure Rating / Limit 60 m
    Equipment used with All except 600R, 6000, 600QS, 600LS, 600OMS
    Medium Fresh and Salt Water
    Monitoring Yes
    Parameters Measured pH, ORP
    Sampling Yes
    User Calibratable Yes
    User Replaceable Yes
    Warranty 1 year

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