Ammonia and ammonium meters for professional water testing. Pacific Sensor Tech supplies Milwaukee PRO photometers that measure ammonia in water to lab-grade accuracy — low range (0.00–3.00 mg/L) for drinking water, environmental sampling and sensitive aquaculture, and medium range (0.00–9.99 mg/L) for wastewater, intensive systems and process monitoring.
These are professional instruments, not aquarium drop kits: direct digital readings in mg/L, no colour cards to interpret, and repeatable results you can put in a compliance record.
Ammonia and ammonium meters for professional water testing. Pacific Sensor Tech supplies Milwaukee...
Ammonia (Medium Range) Professional Photometer
Ammonia (Low Range) Professional Photometer
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Ammonia MR reagent set (100 tests)
Ammonia Low Range reagent set (100 tests)
In water, ammonia exists in two forms that shift with pH and temperature: free ammonia (NH3), which is toxic to fish, and the ammonium ion (NH4+), which is far less so. Together they are reported as total ammonia nitrogen (TAN), or ammonia nitrogen (NH3-N) — the figure most Australian discharge licences and aquaculture protocols are written against.
Milwaukee PRO photometers report ammonia nitrogen (NH3-N) in mg/L, which is directly comparable to TAN limits. If your standard is expressed as free ammonia, calculate it from the TAN reading using the sample’s pH and temperature.
Ammonia is one of the most closely watched parameters in water quality because it is toxic to aquatic life at low concentrations and is a direct indicator of biological load. In aquaculture it is often the parameter that limits stocking density, and it is typically tested daily. In municipal water and wastewater treatment it is measured against discharge licence limits and used to control the nitrification process. In environmental and catchment monitoring it tracks nutrient runoff from agricultural land. In hydroponics and intensive agriculture it is monitored in nutrient solutions and irrigation water.
Because the safe thresholds are low and often legally defined, most of these applications need a direct digital reading in mg/L rather than a colour comparison — which is what a photometer provides.
Yes — the instrument used to measure ammonia in water is a photometer, also called a colorimeter. You add a reagent to a water sample, which develops a colour in proportion to the ammonia present. The meter then passes a fixed wavelength of light through the sample, measures how much is absorbed, and converts that directly into a concentration in mg/L.
Pacific Sensor Tech supplies the Milwaukee Mi405 PRO and Mi407 PRO ammonia photometers. Both use an adaptation of the Nessler method with a blue LED light source at 466 nm, report ammonia nitrogen (NH3-N) in mg/L to a resolution of 0.01 mg/L, and give a direct digital reading with no colour chart to interpret.
In water, ammonia exists in two forms that shift with pH and temperature: free ammonia (NH3), which is the toxic form, and the ammonium ion (NH4 +), which is far less harmful. Raising pH or temperature pushes the balance toward free ammonia.
Because the two forms interconvert, laboratories and licences usually report them together as total ammonia nitrogen (TAN), or ammonia nitrogen (NH3-N). The Milwaukee Mi405 PRO and Mi407 PRO report ammonia nitrogen (NH3-N) in mg/L, which is directly comparable to a TAN limit. If your standard is written in terms of free ammonia instead, calculate it from the NH3-N reading using the sample's pH and temperature.
Choose by the concentrations you expect to see. The Mi407 PRO (low range) measures 0.00 to 3.00 mg/L NH3-N with an accuracy of ±0.09 mg/L at 1.50 mg/L. Its tighter accuracy makes it the right choice for drinking water, environmental and catchment sampling, hatcheries, and any application where the threshold you are testing against sits close to zero.
The Mi405 PRO (medium range) measures 0.00 to 9.99 mg/L NH3-N with an accuracy of ±0.30 mg/L at 5.00 mg/L. Its wider span suits wastewater, intensive aquaculture grow-out systems and process monitoring, where readings routinely sit above the low-range ceiling.
Both meters are the same price, so the decision is purely about range and accuracy, not budget. If your readings straddle 3 mg/L, choose the medium range so you are not driving the instrument off scale.
A photometer measures light absorbance electronically and returns a numeric result — 0.01 mg/L resolution, with a stated accuracy of ±0.09 mg/L on the Mi407 PRO and ±0.30 mg/L on the Mi405 PRO. A drop-based test kit relies on the operator matching a developed colour against a printed chart by eye, so the result depends on lighting, eyesight and judgement, and typically resolves only to the nearest step on the chart.
For a hobby aquarium, a colour chart is usually adequate. For a compliance record, a discharge licence, a research dataset or a commercial aquaculture operation, a numeric reading that another operator can reproduce is normally required.
Yes, a reagent is required for every test, and both meters ship with reagents included. The Mi405 PRO is supplied complete with reagents for 100 tests, two cuvettes, a hard carrying case, wiping tissue and a 9 V battery. The Mi407 PRO is supplied on the same basis. When the starter reagents run out, order the replacement kit that matches your meter's range — the two are not interchangeable. The Mi505-100 is the medium range replacement kit for the Mi405 PRO, and the Mi507-100 is the low range replacement kit for the Mi407 PRO. Each contains NH3-1 and NH3-2 (2 × 20 ml) and covers 100 tests.
