6425AF Anti-Fouling Chlorophyll 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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Predict algae blooms and determine the nutrient loading in water with the YSI 6425AF Chlorophyll Sensor.

This sensor must be installed into a 6-Series sonde to function. Does not function on its own.

  • Overview

    Copper-based parts on the YSI 6425AF Chlorophyll Sensor repel aquatic growth on sensors, extending deployment periods.

    The probe is designed to estimate phytoplankton concentrations by detecting the fluorescence from chlorophyll in situ. The data can be useful in predicting detrimental algae blooms and, indirectly, in determining nutrient loading in environmental applications. The probe features a mechanical self-wiping capability for long-term monitoring.

    The YSI 6425AF Chlorophyll Probe uses technology similar to that used by fluorometers, but the YSI sensor is much smaller, making it compatible with the probe ports in YSI's 6-Series instruments, including the YSI 6600 & 6600 V2 as well as the YSI 6820, 6820 V2, 6920, & 6920 V2. The YSI 6600 V2 sonde allows simultaneous measurement of four optical probes (dissolved oxygen, turbidity, chlorophyll, blue-green algae, and/or rhodamine), along with other parameters. The YSI 6820 V2 and 6920 V2 allow measurement of two optical probes, along with many other parameters.

    Features include:

    • Fast, convenient, in-situ monitoring
    • Self-wiping probe for long-term measurement
    • Small field-replaceable probe design

    Chlorophyll in various forms is bound within the living cells of algae, phytoplankton, and other plant matter found in water. Chlorophyll is a key component in the process of photosynthesis, the critical process in which energy from sunlight is used to produce life-sustaining oxygen. The amount of chlorophyll in a water sample is used as a measure of suspended phytoplankton, the magnitude of which can significantly affect the overall quality of water. Before this YSI sensor made in situ measurement convenient, the common way to measure chlorophyll was to collect samples and use extractive analysis in a laboratory, or take large equipment to the field. Extractive analysis methods, though highly accurate, are time-consuming and require an experienced analyst. The YSI optical, fluorescence probe is quick and efficient to use, and enables spot sampling in remote areas as well as continuous or interval monitoring.

    Notable Specifications:

    • Range: ~0 to 400 ug/L; 0 to 100 RFU
    • Detection Limit: ~0.1 ug/L
    • Resolution: 0.1 ug/L Chl; 0.1% RFU
    • Linearity: R2> 0.9999

  • Specifications
    Anti Fouling Yes
    Depth / Pressure Rating / Limit 200 m
    Equipment used with 600OMS, 6920V2, 6820, 6600V2, 6920, 6600EDS, 6600, 6820V2, ADV6600
    Monitoring Yes
    Parameters Measured


    User Calibratable Yes
    User Replaceable Yes

    2 years

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