6561 pH 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 measurement in sensors designed for minimal maintenance in sampling, profiling, and long-term monitoring applications.

This sensor must be installed into a 6-Series 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.

    6561 pH Sensor:
    The YSI 6561 pH sensor features a 'long-life' sealed gel reference, eliminating the need to refill. For high-fouling applications, the 6561FG'flat glass' sensor is available for wiped antifouling protection on the 6600EDS V2. 6565 pH/ORP Probe also available.


    • Produces very stable readings.
    • Rugged and guarded. 


    • Not wipeable; not ideal for high-fouling environments.

    Sensor is available for use on the following sondes:

    • 600XL & 600XLM and 600XL & 600XLM V2
    • 600DW & 6920DW
    • 6820 V2 & 6920 V2
    • 6600 V2 & 6600EDS V2

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

    U.S. EPA ETV

  • Specifications

    ±0.2 unit

    Depth / Pressure Rating / Limit 60 m
    Equipment used with 600OMS, 600LS, All except 600R, 600QS, 6000
    Medium Fresh and Salt Water
    Monitoring Yes
    Operating pH Range 0 to 14 units
    Parameters Measured pH
    Sampling Yes
    User Calibratable Yes
    User Replaceable Yes
    Warranty 1 year

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