Water Quality System (WQS)
Field & Laboratory Meters
  • pH, SCT, DO & BOD, Multi-parameter Testing
Environmental Monitoring Systems (EMS)
Multi-parameter Water Quality Sondes
  • Sampling, Logging& Profiling

Integrated Systems & Services (ISS)
Environmental Monitoring Modules
  • Buoy& Floating Platforms, Profiling Systems, EcoMapper AUV

EMS_6 Series and EXO Water Quality Sondes

pH Sensor
Combination pH and Gel Reference in a Single Sensor

Simple, accurate pH measurement in a sensor designed for minimal maintenance.

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.

YSI pH 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.

This sensor is available for use on the following sondes:

  • 600R & 600QS (non-field replaceable version, not shown)
  • 600XL & 600XLM
  • 600DW & 6920DW
  • 6820 V2 & 6920 V2
  • 6600 V2 & 6600EDS V2

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

You can rely on the accuracy and reliability of YSI's sensor technology - the performance of the 6561 sensor has been ETV Verified.*

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