Monitor water quality with confidence using the Milwaukee pH55 PRO Waterproof Digital pH and Temperature Tester. Designed for convenient, reliable water testing, this professional pocket-sized instrument measures both pH and temperature simultaneously, making it an excellent choice for aquarium owners, aquaculture professionals, hydroponics and general water quality monitoring.

Featuring a waterproof IP65-rated housing, automatic temperature compensation (ATC) and an easily replaceable double-junction pH electrode, the Milwaukee pH55 PRO combines practical functionality with durable construction.

Its large dual-level LCD display provides clear pH and temperature readings at the same time, helping you monitor important water parameters quickly and easily.

With an extended pH measurement range of -2.0 to 16.0 and an accuracy of ±0.1 pH, the pH55 PRO offers a convenient alternative to traditional colour-based water testing kits.

Whether you're maintaining a freshwater aquarium, monitoring an aquaculture system, managing a koi pond or checking hydroponic nutrient solutions, the Milwaukee pH55 PRO provides a practical solution for routine water testing.

Key Features & Benefits

• Simultaneous pH & Temperature Measurement: Displays pH and temperature readings together on its large dual-level LCD screen.

• Automatic Temperature Compensation (ATC): Automatically compensates pH measurements for temperature variations.

• Waterproof IP65 Construction: Designed to withstand water exposure and splashes during routine testing.

• Replaceable pH Electrode: Features a replaceable Milwaukee Mi56P double-junction electrode, extending the useful life of the instrument.

• Wide pH Measurement Range: Measures from -2.0 to 16.0 pH, providing flexibility across different water testing applications.

• Accurate Measurements: Offers ±0.1 pH accuracy and ±0.5°C temperature accuracy.

• Automatic Calibration: Simple automatic one- or two-point calibration with two sets of pre-programmed buffer values.

• Large Dual-Level LCD: Easily view pH and temperature measurements simultaneously.

• Stability Indicator: Indicates when measurements have stabilised.

• Hold Function: Freezes the displayed reading for convenient recording.

• Long Battery Life: Provides approximately 300 hours of operation.

• Compact & Portable: Lightweight pocket-sized design suitable for everyday testing and field use.

Ideal Applications

The Milwaukee pH55 PRO is suitable for a wide range of water quality monitoring applications.

Aquariums & Fish Tanks

Regular pH and temperature monitoring helps aquarium owners maintain stable water conditions for freshwater and marine fish.

Aquaculture & Fish Farming

Monitor pH and temperature in fish tanks, hatcheries and aquaculture systems as part of a routine water quality management programme.

Koi Ponds & Garden Ponds

Check pond water pH and temperature to help maintain suitable environmental conditions for fish and aquatic life.

Hydroponics

Monitor the pH of nutrient solutions to help maintain appropriate growing conditions and nutrient availability for plants.

Horticulture & Agriculture

Useful for checking water and growing solution pH in horticultural and agricultural applications.

Swimming Pools & Water Treatment

A convenient digital instrument for monitoring pH as part of routine water quality management.

Why Measure pH and Temperature Together?

Water temperature influences pH measurements and is an important parameter in aquatic environments.

The Milwaukee pH55 PRO incorporates automatic temperature compensation, adjusting the pH measurement according to the temperature of the sample within the instrument's specified operating range.

The dual-level LCD also allows you to view both readings simultaneously.

This makes it particularly useful for aquarium and aquaculture applications where understanding both pH and temperature helps provide a clearer picture of changing water conditions.

Replaceable Double-Junction pH Electrode

One of the main advantages of the Milwaukee pH55 PRO is its replaceable Mi56P double-junction pH electrode.

All pH electrodes gradually deteriorate through normal use, ageing and contamination. Eventually, this can lead to slower response times and reduced measurement performance.

The pH55 PRO features a modular electrode design, allowing the electrode to be replaced without having to purchase an entirely new meter.

Benefits include:

• Extends the useful working life of the tester.

• Allows replacement of worn or damaged electrodes.

• Reduces the need to replace the complete instrument.

• Provides a practical long-term solution for regular water testing.

The replacement electrode is the Milwaukee Mi56P, compatible with the pH55 and pH56 testers.

Technical Specifications

Specification	Details
Brand	Milwaukee Instruments
Model	pH55 PRO
Measurement Parameters	pH & Temperature
pH Measurement Range	-2.0 to 16.0 pH
pH Resolution	0.1 pH
pH Accuracy	±0.1 pH
Temperature Range	-5.0 to 60.0°C
Temperature Resolution	0.1°C / 0.1°F
Temperature Accuracy	±0.5°C / ±1°F
Temperature Compensation	Automatic (ATC)
Calibration	Automatic, 1- or 2-point
Buffer Options	Standard and NIST buffer sets
Electrode	Milwaukee Mi56P
Electrode Type	Replaceable double-junction
Waterproof Rating	IP65
Display	Dual-level LCD
Stability Indicator	Yes
Hold Function	Yes
Battery Type	4 × 1.5V LR44 / A76
Battery Life	Approximately 300 hours
Auto Power Off	After 8 minutes of inactivity
Weight	Approximately 100 g

Easy Automatic Calibration

The Milwaukee pH55 PRO features automatic one- or two-point calibration, making it straightforward to maintain measurement accuracy.

Two sets of pre-programmed calibration buffers are available:

Standard buffer set:

• pH 4.01

• pH 7.01

• pH 10.01

NIST buffer set:

• pH 4.01

• pH 6.86

• pH 9.18

The meter automatically recognises the calibration buffer values, helping simplify the calibration process.

For routine aquarium and aquaculture water testing, two-point calibration using pH 7.01 and pH 4.01 is a suitable choice when monitoring predominantly neutral to acidic water conditions.

Electrode Maintenance & Care

Proper electrode maintenance is essential for maintaining reliable pH measurements and extending electrode life.

We recommend:

• Store the electrode with Milwaukee MA9015 storage solution.

• Never store the electrode in distilled or deionised water.

• Clean the electrode periodically using Milwaukee MA9016 cleaning solution.

• Calibrate regularly and after cleaning or prolonged storage.

• Rinse the electrode with suitable rinse water between samples.

• Replace the electrode when response times become excessively slow or measurement performance deteriorates.

Suitable maintenance products include:

• Milwaukee MA9015 Electrode Storage Solution.

• Milwaukee MA9016 Electrode Cleaning Solution.

• Milwaukee Mi56P Replacement pH Electrode.

• Milwaukee pH 4.01 Calibration Solution.

• Milwaukee pH 7.01 Calibration Solution.

• Milwaukee pH 10.01 Calibration Solution.

What's Included?

The standard Milwaukee pH55 PRO package includes:

• Milwaukee pH55 PRO pH and temperature tester.

• Replaceable Mi56P pH electrode.

• Protective electrode cap.

• pH 4.01 calibration solution sachet.

• pH 7.01 calibration solution sachet.

• LR44 batteries.

• Instruction manual.

• Protective packaging.

Please check the supplied packaging configuration, as Milwaukee may offer different packaging options.

Why Buy from GroAqua?

GroAqua supplies specialist water quality monitoring equipment for aquariums, aquaculture, horticulture and water treatment applications.

From everyday aquarium testing equipment to professional water monitoring instruments, we help customers find practical solutions for maintaining water quality.

The Milwaukee pH55 PRO is an excellent choice for anyone looking for a waterproof digital pH tester with the added convenience of simultaneous temperature measurement and a replaceable electrode.

Order your Milwaukee pH55 PRO Waterproof pH & Temperature Tester from GroAqua today.