Milwaukee MC125 PRO 2-in-1 Digital pH / ORP Controller

SKU: MC125
Range: 0.00 to 14.00 pH | ORP: ±1000 mV
Resolution: 0.1 pH, 1 mV
Accuracy: ±0.2 pH | ±5 mV
Calibration: Manual 2 point pH only | ORP Factory Calibrated
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The Milwaukee MC125 PRO pH and ORP controller is designed for people looking to measure and adjust pH and ORP levels automatically with one simple controller. Just set your pH and ORP parameters and let the Milwaukee pH Controller do the rest.
The Milwaukee PRO pH / ORP controller is preferred by people looking to dial in their testing program when they have an ongoing need to maintain levels. Common uses are nutrient tanks, aquariums, pools, and spas.
The Milwaukee PRO pH / ORP controller offers:


The Milwaukee PRO 2 in 1 controller offers an accuracy to ±0.2 pH with two point manual calibration and ORP accuracy to ±5 mV.


See real-time pH and ORP measurements from 0.00 pH to 14.00 pH and -1000 mV to 1000 mV with a large LED with easy switching between parameters.


The controller provides a control range of 4 to 8 pH and -200 to 600 mV. Just set your control range and the controller do the rest.


Choose your device including oxygen pumps, CO2-regulators, O3 ozonizers and other pH & ORP control devices by simply plugging the device into the correct pH or ORP outlet.


  • Fast easy to read current results with large digital LCD readout.
  • Accurate to ±0.2 pH and ±5 mV with the user selectable high/low set points.
  • Simple two-point calibration for increased pH accuracy with manual trimmers for easy adjustment.
  • Lab grade, gel-filled, double junction pH electrode and platinum ORP electrode included for low maintenance and high performance.
  • 6.5 feet probe cables for extra flexibility when testing.
  • 12 VDC power supply.


"I run this unit 24/7 and have not had any problems. It keeps my fish tank CO2 injector running perfectly and puts my mind at ease regarding overdosing."


Properly maintaining your pH and ORP probes will give you fast, accurate results for longer. pH and ORP probes are similar in design but there are some differences.
pH probes have a sensing bulb that loses sensitivity with age. All pH sensors have a limited life and response time gets longer with age.
ORP probe have usually a platinum electrode instead of a glass bulb. This electrode has a longer life but can have a residue build up that affect response rates and accuracy.
Both electrodes have a reference junction that can become clogged resulting in slow and inaccurate results. Cleaning and keeping the probe hydrated will help prevent this.
pH Probe
Here are our top four tips for your pH probe.
1. Always store with the cap full of buffer or storage solution not water.
2. Clean your Probe regularly by soaking in cleaning solution.
3. Calibrate after cleaning and/or storage before testing to adjust for changes in the pH sensor.
4. Gently stir the Probe in the sample for a faster result.
ORP Probe
Here are our top three tips for your ORP probe.
1. Always store with the cap full of buffer or storage solution not water.
2. Clean your probe regularly by soaking in cleaning solution.
3. After cleaning return the ORP probe sensor to the tank.
Thank you for considering Milwaukee to help you take your results to the next level.


pH Range: 0.00 - 14.00 pH
ORP Range: ± 1000mV
pH Resolution: 0.01 pH
ORP Resolution: ± 1 mV
pH Accuracy: ± 0.2 pH
ORP Accuracy: ± 5 mV
Set point pH: 4 to 8 pH
Set point ORP: -200 to 600 mV
Calibration: Manual 2 points pH
Alarm Active when reading is higher or lower than set point
pH Dosing Contact
1 power plug for CO2 dosing
ORP Dosing Contact
1 power plug for O3 dosing
pH Electrode: MA911B/2 (included)
ORP Electrode: MA921B/2 (included)
Environment: 0 to 50°C / 32 to 122°F; max RH 95%
Power Supply: 12 VDC adapter (included)
Power Drivers: 115 VAC, 2A, 60Hz or 230 VAC, 1A, 50Hz
Dimensions: 5.8 x 3.25 x 1.26 inches
Weight: 7.1 ounces

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