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

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DESCRIPTION The Milwaukee MC125 PRO pH and ORP controller is designed for people looking to measure and...
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Subtotal: $213.18
  • Seres


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. 


The controller comes with a complete mounting kit including two probe holders.


  • 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. Calibrate after cleaning and/or storage before testing to adjust for changes in the ORP probe sensor.


  • 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


We ship daily from Monday through Friday, and shipments are processed within 24-48 hours of cleared payment.
Orders placed over the weekend are processed on the next business day.

Free Shipping

Specific Vendors offer free shipping over a certain amount. This will be automatically applied during checkout.

Orders over $10,000 before tax qualify for free shipping!

Free Shipping only applies to domestic US (lower 48 states -- sorry, Alaska & Hawaii) shipments.

Shipping Rates

Shipping rates are calculated during checkout based on the weight, dimensions, and destination of the ordered items. We do our best to calculate the exact cost.

Updated 5/1/2023:

Please note that due to the higher shipping costs and larger dimensions of some of our products, our shipping calculator may not always provide an accurate shipping estimate. In these cases, we will reach out to you with an updated shipping quote after you place your order. If you have any questions about shipping costs, please don't hesitate to contact us before placing your order. We apologize for any inconvenience and appreciate your understanding.

Seres reserves the right to notify you of any additional shipping charges. We partner with multiple vendors and locations, which can alter shipping rates. In addition, there are conditions out of our control (rural areas, fuel surcharge, multiple shipments). If this occurs, you will be contacted immediately and have the right to modify or cancel your order for a full refund. 

Address Change / Order Cancellation

If you need to change the shipping address, please get in touch with us at or call 1-877-237-3754

Once the order is shipped, we will do our best to perform an address intercept. You will be charged an Intercept Fee imposed by the shipping carrier. This fee varies from each carrier. Please note not all shipping carriers will accept address intercept changes.

If an order is canceled in transit, you are solely responsible for all shipping charges incurred by the Shipping Carrier.

Shipping charges will not be refunded.


Once an order has been shipped, we will send an email and text message on file with the tracking number. If your order is fulfilled from multiple vendors or locations, you will receive shipment confirmations with tracking for each shipment. 

In addition, you can check the status of your order through the order confirmation email or within your profile page under Track Order.

Freight (LTL)

Scheduled appointments deliver freight shipments. You are responsible for inspecting for damage incurred in transit and signing before the driver leaves. DO NOT accept the shipment if there is any damage. If your freight shipment arrives damaged, contact us immediately.

Once delivered, we cannot reimburse paid freight charges or refund products.

Some restrictions may apply; Hawaii and Alaska do not qualify for free shipping offers.

Damaged Shipment

It rarely happens, but once in a while, products are damaged during Shipping. Therefore, please scrutinize all shipments for damaged or missing items before signing for them (if required).

The shipping carrier is responsible for items damaged during Shipping, which will most often be UPS, FedEx, or USPS. 

If assistance is needed, please get in touch with us immediately. Seres cannot promise refunds or replacements if this is not done within 72 hours. 

By signing your name and accepting shipment for a Freight(LTL) order, you get no reimbursement of freight charges, order costs, or any other charges incurred.

Lead Times

Please note that there is up to a 7-day processing period for orders containing Hawthorne products.


Due to the valuable contents of many products we sell,  the carrier may need a signature upon delivery. Please understand that this is a measure our company took to ensure safe delivery and fraud protection.

Third-Party Carriers will attempt to deliver a signature-required order three times. 

Please follow up with the carrier for assistance if a missed-delivery note is received.

If assistance is needed, please get in touch with us, so we can help contact the carrier. 

Shipping costs will not be refunded for missed shipments.

Seres is not responsible for any missing, lost, or stolen items.

At this time, we do not ship to post office boxes or APO/FPO addresses.  

For more information, please read our Terms of Service.

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