--- title: "Dissolved Ammonia (NH₃) Sensors & Monitoring | Aethair" description: "Ammonia (NH₃) is the un-ionized fraction of total ammonia nitrogen and the form that is acutely toxic to aquatic life. Sensors and monitoring." url: https://aethair.io/parameters/ammonia/ --- Measurements · Water Quality # Dissolved Ammonia (NH₃) Also known as ammonia nitrogen, un-ionized ammonia, unionized ammonia Ammonia (NH₃) is the un-ionized, dissolved form of nitrogen in water, reported in milligrams per liter. [Schedule a call](https://calendly.com/d/ctdd-mkr-v9v/aethair-demo-website) [Configure Dissolved Ammonia (NH₃) Monitoring](https://aethair.io/build/?params=ammonia) At a glance mg/L Water Quality 1 way to measure it - **Thiamis** 5 external instruments What it is ## What is ammonia (NH₃)? Ammonia (NH₃) is the un-ionized, dissolved form of nitrogen in water, reported in milligrams per liter. It is the species that makes ammonia pollution acutely toxic to aquatic life. It exists in a temperature- and pH-dependent equilibrium with ammonium (NH₄⁺). Together the two make up total ammonia nitrogen, but only the un-ionized NH₃ fraction readily crosses fish gill membranes and causes harm. As water becomes warmer and more alkaline, the equilibrium shifts toward NH₃, so a modest total-ammonia concentration that is harmless in cool, acidic water can become lethal in warm, high-pH water. Ammonia enters water from sewage and wastewater, agricultural and slurry runoff, fertilizer, and the decay of organic matter. Like ammonium, it is a sensitive marker of fresh organic and nutrient pollution, but it is the parameter that speaks directly to toxicity. Because it is the toxic fraction that criteria are written against, ammonia is a key parameter in wastewater, river, fisheries, and aquaculture monitoring. ### Health and operational effects Un-ionized ammonia damages the gills and tissues of fish and other aquatic organisms and is lethal above quite low concentrations. Chronic exposure suppresses growth and reproduction well below acute levels. Because the toxic share rises with pH and temperature, the danger of a given nitrogen load is not fixed: the same water can be safe at dawn and harmful by afternoon as temperature and photosynthetic pH swing. A rising ammonia reading is a classic signature of a sewage spill, a slurry input, or a failing biological treatment stage, and in aquaculture it is watched as a primary threat to stock, where even short excursions cause losses. How it is measured ## How Dissolved Ammonia (NH₃) Is Measured Ammonia is not usually measured directly in-situ; it is **derived** on a multiparameter sonde connected to a Thiamis gateway. The sonde reads ammonium with an ion-selective electrode (ISE) and then computes the un-ionized ammonia fraction from that reading together with its pH and temperature channels, using the known dissociation equilibrium. An ammonia value is therefore only as good as the ammonium, pH, and temperature measurements behind it. Electrode drift, ionic interference, and biofouling all carry into the ammonia estimate, so the sonde needs regular cleaning and calibration against standards, and accurate pH and temperature readings are essential. Laboratory methods measure total ammonia nitrogen and calculate the NH₃ share the same way, from pH and temperature. An instrument on Thiamis 5 A third-party instrument connected to a Thiamis gateway, reporting into the same Environet account. ### Placing ammonia sensors Because ammonia is derived from the ammonium ISE, the sonde is placed exactly where ammonium matters: at a representative point downstream of a wastewater outfall, a farm, or a storm drain, or within an aquaculture system. Continuous logging with alarms catches the sharp, transient excursions that follow spills and storm overflows, which grab sampling misses. It is doubly useful here because the toxic fraction tracks the daily pH and temperature cycle, so the timing of an exceedance matters as much as its size. Keep the ISE clean and calibrated and the pH sensor accurate, because both feed the ammonia calculation. ### Every device and option that measures Dissolved Ammonia (NH₃) 5 | Device / option | Type | Base platform | Measures | | - | - | - | - | | [YSI](https://aethair.io/sensors/ysi-water-quality-sondes/) · EXO1, EXO1S, EXO2… | Water Quality Sondes | Thiamis | Dissolved Ammonia (NH₃) [Ammonium (NH₄)](https://aethair.io/parameters/ammonium/) [Blue-Green Algae](https://aethair.io/parameters/bga/) [Chloride](https://aethair.io/parameters/chloride/) [Chlorophyll](https://aethair.io/parameters/chlorophyll/) [Conductivity](https://aethair.io/parameters/conductivity/) [Dissolved Oxygen](https://aethair.io/parameters/do/) | | [In-Situ](https://aethair.io/sensors/in-situ-water-quality-sondes/) · Level TROLL 300, Level TROLL 400, Level TROLL 500… | Water Quality Sondes | Thiamis | Dissolved Ammonia (NH₃) [Ammonium (NH₄)](https://aethair.io/parameters/ammonium/) [Blue-Green Algae](https://aethair.io/parameters/bga/) [Chloride](https://aethair.io/parameters/chloride/) [Chlorophyll](https://aethair.io/parameters/chlorophyll/) [Conductivity](https://aethair.io/parameters/conductivity/) [Density](https://aethair.io/parameters/density/) | | [Eureka Water Probes](https://aethair.io/sensors/eureka-water-probes-water-quality-sondes/) · Manta+ 20, Manta+ 25, Manta+ 30… | Water Quality Sondes | Thiamis | Dissolved Ammonia (NH₃) [Ammonium (NH₄)](https://aethair.io/parameters/ammonium/) [Chloride](https://aethair.io/parameters/chloride/) [Chlorophyll](https://aethair.io/parameters/chlorophyll/) [Dissolved CO₂](https://aethair.io/parameters/dissolved_co2/) [Dissolved Oxygen](https://aethair.io/parameters/do/) [fDOM / CDOM](https://aethair.io/parameters/fdom/) | | [Spectra Scientific](https://aethair.io/sensors/spectra-scientific-water-quality-sondes/) · Spectra Litmus 6, Spectra Litmus 4 | Water Quality Sondes | Thiamis | Dissolved Ammonia (NH₃) [Ammonium (NH₄)](https://aethair.io/parameters/ammonium/) [Blue-Green Algae](https://aethair.io/parameters/bga/) [Chloride](https://aethair.io/parameters/chloride/) [Chlorophyll](https://aethair.io/parameters/chlorophyll/) [Conductivity](https://aethair.io/parameters/conductivity/) [Density](https://aethair.io/parameters/density/) | | [YSI](https://aethair.io/sensors/ysi-water-quality-sondes/) · 6600 V2, 6600EDS V2, 6920 V2… | Water Quality Sondes | Thiamis | Dissolved Ammonia (NH₃) [Ammonium (NH₄)](https://aethair.io/parameters/ammonium/) [Blue-Green Algae](https://aethair.io/parameters/bga/) [Chloride](https://aethair.io/parameters/chloride/) [Chlorophyll](https://aethair.io/parameters/chlorophyll/) [Conductivity](https://aethair.io/parameters/conductivity/) [Dissolved Oxygen](https://aethair.io/parameters/do/) | [Configure Dissolved Ammonia (NH₃) Monitoring](https://aethair.io/build/?params=ammonia) Where it is monitored ## Solutions That Monitor Dissolved Ammonia (NH₃) Each one links to the solution page showing what that industry measures it for. ### [Aquaculture & Fish Farming](https://aethair.io/solutions/aquaculture/) Often added Dissolved oxygen, temperature, and ammonia control Related ## More in Water Quality [Water Temperature](https://aethair.io/parameters/water_temperature/) [pH](https://aethair.io/parameters/ph/) [ORP](https://aethair.io/parameters/orp/) [Specific Conductance](https://aethair.io/parameters/specific_conductance/) [Salinity](https://aethair.io/parameters/salinity/) [TDS](https://aethair.io/parameters/tds/) [Turbidity](https://aethair.io/parameters/turbidity/) [Dissolved Oxygen](https://aethair.io/parameters/do/) [Chlorophyll](https://aethair.io/parameters/chlorophyll/) [Nitrate (NO₃)](https://aethair.io/parameters/nitrate/) [Ammonium (NH₄)](https://aethair.io/parameters/ammonium/) [Chloride](https://aethair.io/parameters/chloride/) Questions ## Dissolved Ammonia (NH₃) FAQ Is ammonia the same as ammonium? No. Ammonium (NH₄⁺) is the ionized form and ammonia (NH₃) the un-ionized form, and they exist together in a pH- and temperature-dependent equilibrium as total ammonia nitrogen. The distinction matters because only un-ionized ammonia is strongly toxic to aquatic life, which is why the two are reported as separate parameters. Why is ammonia measured rather than just ammonium? Because ammonia is the toxic species and the one that water-quality limits are written against. Ammonium alone does not show the hazard. The un-ionized ammonia fraction, computed from ammonium, pH, and temperature, does, and it can vary widely for the same total nitrogen as conditions change. Why does un-ionized ammonia rise with pH and temperature? The NH₃ ⇌ NH₄⁺ equilibrium shifts with both: warmer, more alkaline water pushes more of the total toward un-ionized NH₃. So the same total ammonia is far more dangerous in warm, high-pH water, and the toxic fraction can swing over a single day as temperature and photosynthetic pH change. How do I monitor ammonia? Deploy a multiparameter sonde with an ammonium ion-selective electrode plus pH and temperature sensors, connected to a Thiamis gateway. The sonde derives un-ionized ammonia continuously; set alarms and keep to regular cleaning and calibration. Use the configurator to pair a logger with a sonde covering ammonia alongside ammonium, nitrate, pH, and temperature.