The Milwaukee MW301 PRO is a portable conductivity meter designed to measure electrical conductivity (EC) in water and other liquid samples. With a low-range measurement capability of up to 1,999 µS/cm, 1 µS/cm resolution and automatic temperature compensation, it provides a practical way to monitor changes in dissolved ionic content.

For aquarium keepers, the MW301 PRO is useful for comparing tap water, reverse osmosis (RO) water and prepared aquarium water, as well as monitoring conductivity changes in freshwater systems.

Supplied with a separate SE510 conductivity probe, 1-metre cable and calibration solution, the MW301 PRO is also suitable for hydroponics, agriculture, water conditioning, education and laboratory applications.

Low-range conductivity measurement

The MW301 PRO measures electrical conductivity from 0 to 1,999 µS/cm, with a resolution of 1 µS/cm.

Conductivity indicates how readily water conducts electricity. It is influenced by the concentration of dissolved ions, including minerals and salts.

Monitoring EC can help identify changes in water composition and consistency, making it a useful supporting measurement for aquarium water preparation and general water-quality monitoring.

Useful for freshwater aquarium monitoring

Conductivity is an important supporting measurement for understanding changes in freshwater chemistry.

The MW301 PRO can help aquarium keepers:

• Compare conductivity in tap water and reverse osmosis water.

• Check prepared water before aquarium water changes.

• Monitor changes in dissolved ionic content over time.

• Compare conductivity between different freshwater aquariums.

• Check the consistency of water used for fishkeeping and aquaculture.

• Monitor changes in water conditioning and treatment processes.

Conductivity does not identify individual minerals or contaminants, and an EC reading alone cannot establish whether aquarium water is suitable for a particular species.

Automatic temperature compensation

Water conductivity changes with temperature. The MW301 PRO incorporates automatic temperature compensation (ATC) from 5 to 50°C, helping compensate for temperature-related variations during measurement.

This supports more consistent readings when comparing water samples taken at different temperatures within the compensation range.

Separate SE510 conductivity probe with 1-metre cable

The MW301 PRO is supplied with a separate Milwaukee SE510 conductivity probe connected to the meter by a 1-metre cable.

This allows the probe to be immersed in a sample while the digital display remains outside the container.

The probe is replaceable, helping extend the useful life of the meter without replacing the complete instrument.

For reliable measurements, rinse the probe after use and follow the manufacturer's cleaning and maintenance instructions.

Simple manual calibration

The MW301 PRO uses manual one-point calibration with a 1413 µS/cm conductivity standard.

The instrument is supplied with a calibration solution sachet and a small screwdriver for adjusting the calibration control.

For consistent results, recalibrate regularly and whenever the probe or battery is changed. Use fresh calibration solution and follow Milwaukee's calibration procedure.

Portable design for practical water testing

The MW301 PRO features a compact handheld design and a large digital display for straightforward conductivity measurement.

Additional features include:

• 0–1,999 µS/cm conductivity range.

• 1 µS/cm resolution.

• Automatic temperature compensation.

• Manual calibration adjustment.

• Separate replaceable conductivity probe.

• 1-metre probe cable.

• Approximately 300 hours of battery operation.

• 9V alkaline battery supplied.

Technical specifications

Specification	Milwaukee MW301 PRO
Measurement parameter	Electrical conductivity (EC)
Conductivity range	0–1,999 µS/cm
Conductivity resolution	1 µS/cm
Accuracy at 25°C	±2% of full scale
Calibration	Manual, one point
Calibration standard	1413 µS/cm
Temperature compensation	Automatic
Compensation range	5–50°C
Probe	Milwaukee SE510 conductivity probe
Probe cable	1 metre
Operating environment	0–50°C
Maximum relative humidity	95%
Battery	1 × 9V alkaline
Approximate battery life	300 hours
Meter dimensions	143 × 80 × 32 mm
Meter weight	Approximately 220 g including battery

Supplied with

• Milwaukee MW301 PRO conductivity meter.

• SE510 conductivity probe.

• 1-metre probe cable.

• 20 ml sachet of 1413 µS/cm calibration solution.

• Calibration adjustment screwdriver.

• 9V alkaline battery.

• Instructions.

Recommended accessories

• Milwaukee SE510 replacement probe – replacement conductivity electrode with DIN connector and 1-metre cable.

• Milwaukee M10031B calibration solution – 1413 µS/cm conductivity calibration solution in individual 20 ml sachets.

• Milwaukee MA9061 calibration solution – 1413 µS/cm conductivity calibration solution in a 230 ml bottle.

• Milwaukee MA950 wall mounting kit – optional mounting accessory for the meter.

The Milwaukee MW301 PRO is a practical choice for aquarium keepers, aquaculture operators and water-quality professionals who need a portable, low-range conductivity meter with automatic temperature compensation and a replaceable measuring probe.