The Milwaukee CD601 is a compact, easy-to-use electrical conductivity (EC) tester for checking water quality in aquariums, aquaculture systems, pools, water treatment applications and more.

Designed for quick, routine measurements, the CD601 measures conductivity across a range of 0 to 1,990 µS/cm. Its automatic temperature compensation helps account for temperature differences during testing, while straightforward one-point calibration makes it simple to maintain reliable measurements.

Whether you are monitoring aquarium water, checking freshwater systems or carrying out routine water-quality checks, the CD601 provides a convenient way to keep track of conductivity.

Key Features

• 0–1,990 µS/cm EC range – suitable for low-to-moderate conductivity water applications.

• 10 µS/cm resolution – displays conductivity changes in practical increments.

• Automatic Temperature Compensation (ATC) – compensates for temperature variation from 5 to 50°C.

• Simple one-point calibration – manual calibration using the calibration trimmer and the appropriate standard solution.

• Compact pocket-sized design – convenient for routine checks and portable use.

• Factory calibrated – supplied ready for use, with the ability to recalibrate when required.

• Long battery life – approximately 300 hours of use from four included 1.5V alkaline batteries.

Why Measure Electrical Conductivity?

Electrical conductivity indicates how readily water conducts an electrical current, which is influenced by the concentration of dissolved ions.

Regular EC measurements can help aquarium keepers and aquatic professionals monitor changes in water composition, compare water sources and check consistency during water preparation or treatment.

For aquaculture and aquarium applications, conductivity readings can be useful as part of a wider water-quality monitoring routine. EC should be considered alongside other relevant parameters, such as pH, temperature, dissolved oxygen and ammonia.

Automatic Temperature Compensation

Water conductivity changes with temperature. The CD601 features automatic temperature compensation from 5 to 50°C, helping to make readings more consistent when sample temperatures vary.

Simple Calibration

The CD601 can be recalibrated at a single point using the recommended Milwaukee M10031B 1413 µS/cm conductivity calibration solution.

Calibration is performed manually using the adjustment trimmer and a small screwdriver. Regular calibration helps maintain confidence in measurements, particularly where the tester is used frequently.

EC and TDS: Understanding the Difference

The CD601 measures electrical conductivity (EC) in µS/cm. It does not directly measure total dissolved solids (TDS) in ppm.

EC readings can be used to estimate TDS, but the conversion depends on the factor or scale being applied. Different conversion factors can produce different ppm values from the same conductivity reading. For accurate water analysis, it is important to understand which measurement your application requires.

If you need a dedicated TDS tester with a direct ppm reading, consider the Milwaukee CD600 instead.

Care and Maintenance

To help maintain reliable performance:

• Rinse the sensing area with clean water after each use.

• Avoid allowing nutrient deposits or other residue to build up on the sensor.

• Keep the protective cap in place when the tester is not being used.

• Calibrate periodically, and whenever readings become questionable.

• Use fresh calibration solution for best results.

Technical Specifications

Supplied with

• Milwaukee CD601 conductivity tester

• Protective cap

• Calibration screwdriver

• Batteries

• Instruction manual

A practical, economical EC tester for routine water conductivity checks. The Milwaukee CD601 combines simple operation, automatic temperature compensation and convenient pocket-sized portability for aquarium, aquaculture and general water-quality applications.