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Ammonia - Ammonium

Ammonium (NH4+) — or its uncharged form ammonia (NH3) — is a form of nitrogen which aquatic plants can absorb and incorporate into proteins, amino acids, and other molecules. High concentrations of ammonium can enhance the growth of algae and aquatic plants. Bacteria can also convert high ammonium to nitrate (NO3-) in the process of nitrification, which lowers dissolved oxygen.

A van der Waals' surface coloured according to charge, superimposed on a ball-and-stick model of the ammonia molecule, NH<sub>3</sub>.  Public domain.
A van der Waals' surface coloured according to charge, superimposed on a ball-and-stick model of the ammonia molecule, NH<sub>3</sub>.  Public domain.A van der Waals' surface coloured according to charge, superimposed on a ball-and-stick model of the ammonia molecule, NH<sub>3</sub>.  Public domain. YSI 6883 Ammonia - Ammonium ISE Sensor for 6-Series SondesYSI 6883 Ammonia - Ammonium ISE Sensor for 6-Series Sondes YSI 1004 Ammonium Sensor for Pro SeriesYSI 1004 Ammonium Sensor for Pro Series


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The YSI ammonium sensor consists of a silver/silver chloride wire electrode in a custom filling solution. The internal solution is separated from the sample medium by a nonactin membrane, which selectively interacts with ammonium ions.

Ammonia in water is either un-ionized ammonia or the ammonium ion.  Typically, the value reported is the sum of both forms and is reported as total ammonia or simply - ammonia.  The relative proportion of the two forms present in water is highly affected by pH.

Un-ionized ammonia is the toxic form and predominates when pH is high.  Ammonium ion is relatively non-toxic and predominates when pH is low.  In general, less than 10% of ammonia is in the toxic form when pH is less than 8.0 pH units.  This proportion increases dramatically as pH increases.

The equilibrium between NH3 and NH4+ is also affected by temperature.  At any pH, more toxic ammonia is present in warmer water than in cooler water.

YSI 6600V2 Comprehensive Monitoring System - View of Sensor Configuration


Make the most of your environmental monitoring.


The YSI 6600 V2 data sonde is the most comprehensive water quality monitoring equipment available with simultaneous measurement of conductivity (salinity), temperature, depth or level, pH/ORP plus...


YSI 6920 V2-2 sensor view showing Temperature/Conductivity, Chloride, pH, as well as Optical DO and Turbidity.

6920 V2

Compact Data Sonde for Unattended Monitoring


The YSI 6920 V2 sonde is an economical water quality logging system, ideal for long-term in situ monitoring and profiling.

Real-time turbidity monitoring, dissolved oxygen monitoring, algae monitoring, and more.


YSI 6820 V2 showing sensors, starting clockwise from top: ROX Optical Dissolved Oxygen, Turbidity, pH, ISE, and temperature/condutivity.

6820 V2

Compact Sonde for Field Sampling


The YSI 6820 V2 is a cost-effective data sonde for profiling and spot-checking water quality in rivers, lakes, wetlands, wells, estuaries, and coastal waters.


    YSI Professional Plus Shown with Single Parameter Cable and Probe Assembly

    Professional Plus

    Handheld Multiparameter Instrument


    The YSI Professional Plus handheld multiparameter meter provides extreme flexibility for the measurement of a variety of combinations for dissolved oxygen, conductivity, specific conductance, salinity, resistivity, total dissolved solids (TDS), pH, ORP, pH/ORP combination, ammonium (ammonia), nitrate, chloride and temperature. Also a very powerful lab instrument for BODs, pH and ORP.


    YSI IQ SensorNet 2020 XT Wastewater Monitoring System

    IQ SensorNet 2020 XT

    Improve Operational Efficiency with Continuous Data

    With an easily scalable solution, the 2020 XT allows for the connection of up to 20 sensors. This modular plug-and-play system allows you to monitor the water quality in your wastewater system continuously and accurately.

    "The simple cabling infrastructure - being able to run one cable that provides both power and data-transfer made so much sense."


    YSI IQ Sensor Net 182 XT Stacked on Modules

    IQ SensorNet 182 Models

    Improve Operational Efficiency with Continuous Data

    With an easily scalable solution the 182, 182 XT, and 182 XT-4 allow for the connection of 1-4 sensors depending on which terminal you choose. Add sensors at any time and at any location or change them out with ease. This completely modular plug-and-play system allows you to monitor the water quality in your wastewater or aquaculture system continuously and accurately.


    YSI TruLab 1320 pH, mV, ORP, ISE and Temperature Lab Meter

    TruLab 1320 and 1320P

    Laboratory Instrument for pH, mV (ORP), ISEs and temperature

    Perform accurate lab pH, mV (ORP), ISE and temperature measurements with the YSI 1320 and 1320P with printer.


    YSI chloride, ammonium, and nitrate sensors

    6882, 6883, 6884 Nutrient Ion-Selective-Electrode Sensors (6-Series)

    Measure Nutrient Data with Nitrate, Ammonium, and Chloride with Ion Selective Electrodes


    YSI IQ SensorNet AmmoLyt Sensor

    IQ SensorNet AmmoLyt® Plus 700 Series IQ Sensors

    Digital AmmoLyt® ammonium, potassium sensor


    YSI IQ SensorNet VARiON Sensor

    IQ SensorNet VARiON® Plus 700 Series IQ Sensors

    Digital VARiON® ammonium, nitrate, potassium sensor


    YSI Laboratory ISE Product Family

    Laboratory ISE Electrodes

    Wide selection of 15 electrodes for laboratory ISE measurements.




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