Milwaukee MW103 PRO+ Portable 2-in-1 pH/pHmV/Temperature Meter

Specifications

Accurate pH measurement is about more than the number displayed on the screen. The reliability of every reading depends on the condition of the pH electrode behind it – and over time, contamination, ageing, a clogged junction or loss of sensitivity can affect how quickly and accurately that electrode responds.

The Milwaukee MW103 PRO+ Portable pH/pHmV/Temperature Meter is designed for users who need more insight into their pH measurements. In addition to accurate pH and temperature measurement, the MW103 PRO+ features a dedicated pHmV mode that allows you to evaluate the condition of the pH electrode itself by checking its offset and slope.

That makes the MW103 PRO+ especially useful in applications where reliable pH measurement is critical – from brewing, winemaking and hydroponics to laboratories, water treatment, food production and environmental testing.

With a wide -2.00 to 16.00 pH measurement range, ±0.02 pH accuracy, automatic temperature compensation and automatic 1- or 2-point calibration, the MW103 PRO+ combines laboratory-grade measurement performance with the flexibility of a portable meter. The separate MA831R temperature probe provides the temperature information required for ATC and can also be used for direct temperature measurement.

Why Choose the Milwaukee MW103 PRO+?

• Built-in pH Electrode Health Check: The dedicated pHmV mode allows you to evaluate electrode offset and slope, helping identify an electrode that may need cleaning, conditioning or replacement.
• High-Accuracy pH Measurement: Measure from -2.00 to 16.00 pH with 0.01 pH resolution and ±0.02 pH accuracy.
• Precise pHmV Measurement: The meter provides a ±200.0 mV pHmV range, 0.1 mV resolution and ±0.5 mV accuracy for evaluating pH electrode response.
• Automatic Temperature Compensation: The included MA831R temperature probe enables automatic compensation of the pH reading for changes in sample temperature.
• Independent Temperature Measurement: Switch between pH, pHmV and temperature readings, with temperature displayed in either °C or °F.
• Automatic 1- or 2-Point Calibration: Calibration is simple and repeatable, while two-point calibration provides better characterization of electrode response across the working pH range. The meter supports calibration using pH 7.01 together with pH 4.01 or pH 10.01 depending on the measurement range.
• SE220 pH Electrode Included: The meter is supplied with the lab-grade double junction SE220 pH electrode, providing a low-maintenance solution for general-purpose pH measurement.
• Flexible Electrode Options: The BNC electrode connection allows the meter to be paired with suitable application-specific pH electrodes. For specialized applications, use a compatible pH electrode appropriate for the sample and measurement method. For example, Milwaukee recommends the optional MA919B/1 pH electrode for wine applications.
• Portable and Easy to Operate: A clear digital display, straightforward controls and separate pH and temperature probes make the MW103 PRO+ suitable for laboratory, production and on-site measurements.
• Long Battery Life: Powered by a standard 9 V alkaline battery, the meter provides approximately 750 hours of use, with automatic shut-off after 8 minutes of inactivity to conserve battery power.

Applications

The combination of accurate pH measurement, automatic temperature compensation and pH electrode diagnostics makes the MW103 PRO+ suitable for a wide variety of professional, industrial and technical applications.

Brewing & Beer Production

Accurate mash pH is essential for enzyme activity, extraction efficiency, flavour development and overall brewing consistency. The MW103 PRO+ can be used for brewing water, mash, wort, fermentation and finished-product pH checks, while the electrode health function provides additional confidence that changing readings are not simply the result of a deteriorating sensor.

Hydroponics

In hydroponic systems, nutrient availability is strongly influenced by pH. The MW103 PRO+ is ideal for checking nutrient reservoirs, irrigation solutions, dosing mixtures and recirculating systems, helping growers maintain stable growing conditions.

Winemaking & Enology

pH influences microbial stability, fermentation behaviour, colour, flavour and many other aspects of wine production. The MW103 PRO+ can be used throughout the process for grape juice, must, fermentation and finished wine.

For demanding wine samples, the meter can also be paired with Milwaukee's optional MA919B/1 wine pH electrode, which is specifically designed for this application.

Horticulture & Agriculture

Use the MW103 PRO+ for irrigation water, fertilizer solutions, fertigation systems, nutrient mixtures and prepared soil extracts or slurries, helping growers make informed decisions about plant nutrition and growing conditions.

Laboratories & Research

With its high pH resolution, automatic calibration and separate temperature measurement, the MW103 PRO+ is suitable for routine laboratory analysis, research, quality-control testing, buffer verification and aqueous sample measurement.

The pHmV mode is particularly valuable in environments where electrode performance needs to be checked rather than simply assumed.

Water Treatment & Water Quality

The MW103 PRO+ can support pH monitoring throughout drinking-water treatment, process-water management, purification systems, wastewater treatment and general water-quality testing.

Food Processing

pH is widely used as a process and quality-control parameter in food production. The MW103 PRO+ can be used with suitable electrodes for liquid foods, sauces, ingredients, fermentation products and production-water testing.

For solid, semi-solid, highly viscous or otherwise challenging food samples, an application-specific pH electrode may provide better performance than a general-purpose electrode.

Beverage Production

Monitor pH during the production and quality control of juices, soft drinks, cider, kombucha, fermented beverages, syrups and other liquid products.

Aquaculture & Fish Farming

Stable pH and temperature conditions are important for aquatic organisms. The MW103 PRO+ can be used to check tank water, hatchery systems, recirculating aquaculture systems and fish-farm water.

Aquariums & Reef Systems

Suitable for pH and temperature checks in freshwater aquariums, marine aquariums and reef systems, as well as for testing replacement or prepared water.

Aquaponics

Aquaponic systems must balance the requirements of fish, plants and biological filtration. The MW103 PRO+ provides accurate pH measurement for monitoring the shared water and nutrient cycle.

Ponds & Koi

Use the meter for routine pond-water and koi-system pH monitoring, especially when checking changes following water replacement, seasonal shifts or treatment.

Environmental Water Testing

The portable design makes the MW103 PRO+ suitable for measuring prepared or collected samples from rivers, lakes, groundwater, surface water and wastewater in environmental monitoring applications.

Swimming Pools, Spas & Hot Tubs

The meter can be used for accurate pH verification in swimming pools, spas and hot tubs, supporting routine water-management and treatment checks.

Industrial Process Water & Quality Control

Suitable for general pH testing of process water, rinse water, production solutions and industrial liquid samples, provided that the selected electrode is chemically compatible with the sample.

Fermentation Processes

Beyond brewing and winemaking, the MW103 PRO+ can be used to follow pH changes during kombucha, vinegar and other food or biological fermentation processes.

Education & Training

The MW103 PRO+ is well suited to chemistry, biology, environmental science, agriculture and food-science laboratories, where students can study not only pH and temperature but also the underlying mV response of a pH electrode.

Cosmetics & Personal Care

With an appropriate electrode, the meter can be used during formulation and quality control of liquid cosmetic and personal-care products, including solutions, shampoos and toners.

Pharmaceutical & Biotechnology Laboratories

The MW103 PRO+ can support buffer preparation, aqueous solution testing, research and general laboratory pH checks where its measurement specifications are appropriate for the method being used.

General Chemical & Industrial Laboratory Testing

The wide pH range makes the MW103 PRO+ suitable for routine testing of buffers, acids, bases and other compatible aqueous formulations in general laboratory and industrial QC environments.

Proper pH Meter Care & Maintenance

A pH meter can only perform as well as its electrode. With use, the glass sensing surface gradually loses sensitivity, while sample residue can accumulate on the bulb or block the reference junction. Correct cleaning, storage and calibration therefore play an important role in maintaining fast and reliable measurements.

Storage

Keep the SE220 pH electrode hydrated whenever it is not being used.

For proper storage:

• Store the electrode in Milwaukee MA9015 Storage Solution.
• Keep the protective cap filled with storage solution and securely fitted to the electrode.
• Never store the electrode in distilled, deionized or reverse-osmosis water, as this can damage electrode performance.

If the electrode has been stored dry, rinse it and condition it in MA9015 Storage Solution for several hours – preferably overnight – before calibration and use.

Cleaning

Residue on the sensing bulb or reference junction can cause slow, unstable or inaccurate readings.

For routine maintenance:

• Clean the electrode regularly using MA9016 Electrode Cleaning Solution.
• Organic or dirty samples may require more frequent cleaning.
• Rinse the electrode with purified water after cleaning and before calibration.

If white salt crystals appear around the electrode during storage, this is normal. They can be removed by rinsing the electrode with warm water before use.

Between Measurements

Rinse the pH electrode with purified water between calibration buffers and samples to reduce cross-contamination.

When removing excess liquid, blot the sensor gently with a lint-free tissue – do not rub the glass sensing bulb, as rubbing can affect the electrode and measurement stability.

Calibration

Regular calibration compensates for gradual changes in electrode response and helps maintain measurement accuracy.

• Calibrate the meter regularly according to the accuracy requirements of your application.
• Always calibrate after cleaning and after an extended period of storage.
• Use fresh calibration solutions.
• For most applications, begin with pH 7.01.
• For acidic measurement ranges, use pH 7.01 and pH 4.01 for two-point calibration.
• For alkaline measurement ranges, use pH 7.01 and pH 10.01.
• Although single-point calibration is available, two-point calibration is recommended for higher accuracy.

Use the pHmV Mode as Part of Routine Electrode Maintenance

Calibration tells you whether the meter and electrode can be adjusted to known standards. The MW103 PRO+ goes a step further by allowing you to examine the electrode's actual mV response.

Periodically checking offset and slope can help reveal declining electrode performance before it begins to compromise important measurements. When an electrode shows abnormal behaviour, cleaning and reconditioning should be the first steps; if acceptable response cannot be restored, replacement may be necessary.

The Milwaukee MW103 PRO+ combines accurate portable pH and temperature measurement with something especially valuable for serious pH users – the ability to check whether the electrode producing the measurement is still performing as it should.