Testing Drinking water with an orp meteris important.
See the video on how to do it!

Milwaukee ORP Meter

 Milwaukee Instruments Orp meters measure Oxygen redux potential in any body of water including aquarium.  The Sm500 was a favorite among reefers now called MW500 and uses the Se 300 Replacement Probe  .

Oxidation occurs in water when a one cell takes ions from cell another and then cause  that one to take from another causing it to become a free radical which cascades and the cells break down. By measuring the process it is named ORP (Oxidation Reduction Potential). We Use the Milwaukee orp meterto measure parameters in drinking water in which the theory is with a negative orp will help maintain proper ph balance in the body.  Positive ions oxidize. It measures the tendency of a liquid if the liquid is a oxidative item or free radical.  The higher the number the greater potential for harmful oxidation.   Many Kangan Water tester users use the Milwaukee orp meter mw500 water tester to measure the output of the water filter making sure a low ph.   When testing the water they are testing the acidity or alkalinity of the water plus the oxygen redux potential.

In an aquarium now an orp tester is good for the life of your fish and keeping good health.

High levels can make excessive corrosion, resulting in expensive repairs to your aquarium. This is one parameter that can be measured during the cleaning process for Enagic drinking water filters, swimming pool, pond water, and spa treatments. Corrosion can also be caused by incorrect ph levels and salt corrosion as well so check out our ph testers and salinity refractometers now on sale. By the way if you are a Enagic alkaline water dealer Check out www.AlkalineDemoTank.com for a brand new product.

The reason for using a orp tester is depending on your low level you can kill lower level life forms such as bacteria. You can decrease bad bacteria in an aquarium or by lowering the o.r.p. of the saltwater tank which works the same way in swimming pool or spa water.  This is a great swiming pool tester. It has been proven that the Orp will decrease the longevity of bad bacteria more efficiently than chlorine. In Swimming pools we try to maintain a ph of approx 7.2 through 7.6. This is ideal to decrease chlorine dissapation levels.You must maintain a O.R.P. measurement above 700 mV to kill undesirable organisms.

Typical values mV
Properly chlorinated swimming pool > 700
Salt water aquarium ~ 350
Harmful to aquatic life > 400

Check out the sm500 meter.


Negative Orp Tester Sm500 ORP, Drinking Water Checker Kangen

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Orp Testing is importing for Water Quality. Kangen has recently been the buzz around the health and drinking water industry.

If you are Purchasing an Orp tester for this purpose get the sm500 or Mw500 negative orp meter wholesale see below.  This is the ideal unit made by Milwaukee Instruments.

The interest with with water quality and alkaline has spikes in recent years.  Promoting the positive benefits some users experience with ionized water Enagic came to fruition.  Milwaukee Meters and monitors a brand you love!

Wholesale Orp Meter

Kangen Water® is a trademark of Enagic USA ™ and not affiliated with this website nor do we sell any of their products.

MA9025 ORP Probe Conditioning Kit

Probe Conditioning Kit 
Should be used with a new with the sm500 and sm 600 tester  and new mw500 orp meter ( 2 - 2oz bottles )

This Unit Should Always Be Purchased for New Units to Condition the ORP Mw 500 Probe.


Milwaukee Instruments MW500 Smart ORP Meter, NEW!

Measures negative orp in Drinking water and Fish tanks.

The new Milwaukee mw500 takes place of the sm500 used for testing Negative orp meter.

Milwaukee Instruments MW500 Smart ORP Meter, NEW!

This new model features a faster processor sleeker design and better features when testing your waters orp.
Great for Kangen water testing as well as testing your oxygen redux potential in aquariums and other water solutions.

The Milwaukee mw500 Has many new features

  • Range: ± 1000mV
  • Resolution: 1 mV
  • Accuracy: ± 5 mV
  • Battery type/life: 1 x 9V / 300 hours (Included) 
  • Environment: 0 – 50°C/95% RH Max - Probe: Included
  • MW500 ORP Meter, Range: ± 999 mV by Milwaukee Instruments
  • Faster then the sm500 previous version.

Don't forget the ma9025 Oxidation kit if you are using this to test negative orp in Enagiac water or Kangen type testing as this is required.

Hope this information is helpful to our aquarium folks and kangan distributors and wholesale customers as well.

Kangen Water® is a trademark of Enagic USA ™ and not affiliated with this website nor do we sell any of their products.

MW500 Replaces the SM500



This model is now replaced with the Milwaukee mw 500 orp meter with se300 probe  

Great unit for Testing The Kangen Negative Orp  and Alkalinity or acid property of drinking water. Works great for saltwater aquariums also.

Mw500 is for testing ORP or Oxygen Redux Potential in Drinking water and aquariums.


Milwaukee Instruments Martini ORP57 Waterproof ORP/ºC/ºF Tester, Meter, ORP 57

Milwaukee ORP Meter orp 57


Read inside what you need

Milwaukee Instruments Martini ORP57 Waterproof ORP/ºC/ºF Tester, Meter, ORP 57





The reason we say the orp 57 is not a good fit for testing Kangen water orp properties is this is a dual function orp meter and the solutions needed to oxidize the probe tip for the low readings of Kangen water testing will significantly decrease the tips ability to function long term to work with the ATC portion.

We suggest the MW500 Orp Meter for Enagiac water testing.


Larger picture

Should be used for starting up all ph and orp probes initially and for storage so your electrode probe tip does not dry out. 

Calibrating the Sm 500 or MW 500 by Milwaukee Instruments

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How do i calibrate this orp meter ? 

The SM500  orp meter is factory calibrated  calibrating it does not need to happen.  The MA9020 is a "validation" solution for positive ( + ) ORP.


A good  orp probe should read between 200mv and 275mv -- we consider a probe to be perfect at +235mv to + +245mv in the MA9020 "validation solution"  --


Not to confuse the issue but the SMS510 can be calibrated and the MA9020 is used to "calibrate" that unit.


Many of our customers use this for Kangen Drinking water testing as well

Hope this information is helpful to our aquarium folks and kangan distributers and wholesale customers as well.

Kangen Water® is a trademark of Enagic USA ™ and not affiliated with this website nor do we sell any of their products.

Milwaukee Orp Meter MW500 Orp Questions

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We get a lot of questions on how to use the opr meter so for the sm500 or MW500 orp meter which is our most popular unit we decided to answer some questions.

Does this mean that by putting the probe of the Milwaukee SM500 ORP meter in the Redox solution that it  should read between +200mv and +275mv? and this will validate that the meter is working correctly?


Answer:  Yes - the position we would like to see is 235mv to 250mv.  Remember that this is a test of the POSITIVE side of the mv range and has nothing to do with the NEGATIVE


How much of the orp probe should be immersed and for how long?


Answer:  You only need to insert a inch or two into the solution


Do you read it immediately after the probe is immersed?


Answer:  No, sm500 ORP reading will take about 30 sec to become stable


Does the Redox solution has to be poured into a glass container or can we immerse the probe in the same bottle that the solution comes in?


Answer:  directly into the Redox solution bottle


Does the milwaukee meter have to be TURNED ON when you immerse it Freshwater or Saltwater for testing or do you TURN IT ON after it is immersed?


Answer:  It does not make any difference to the accuracy or speed


After it is taken out of the Redox solution do you rinse it and how/with what (Tap water, bottle water)?


Answer:  either is fine but the prefference is bottle drinking water or RO water


After the probe is out of the Redox solution, how long do we wait to do readings of the water?


Answer: Rinse well as specified above and then go to the solution you want to take a reading on.  Be sure to "Gently" stir the prob in the solution you are reading?


NOTE:  There are several other issues when it comes to using the sm500 ORP meter by milwaukee instruments for checking negative numbers below -50mv not covered above.


Hope this information is helpful to our aquarium folks and kangan distributers and wholesale customers as well.

Kangen Water® is a trademark of Enagic USA ™ and not affiliated with this website nor do we sell any of their products.

General setup Milwaukee sm500 orp User Manual

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User manual PDF MW500 negative ORP meter setup instructions


SM500  ORP Kangen Water

RANGE ±1000 mV



ACCURACY (@25°C) ±5 mV

ORP ELECTRODE MA921B/1 (included)

ENVIRONMENT 0 to 50°C, 95% RH max. BATTERY TYPE 9V alkaline (included)

BATTERY LIFE approximately 300 hours of use

DIMENSIONS 145 x 80 x 40 mm

WEIGHT 220 g (with battery) meter only





M10000B Electrode rinse solution, 20 ml sachet (25 pcs) MA9015 Electrode storage solution, 220 ml bottle MA9020 200-275 mV ORP solution, 220 ml bottle MA921B/1 Platinum ORP electrode with 1 m cable





This instrument is warranted from all defects in materials and manufacturing for a period of two years from the date of purchase. The electrode is warranted for a period of 6 months. If during this period, the repair or replacement of parts is required, where the damage is not due to negligence or erroneous operation by the user, please return the parts to either dealer or our office and the repair will be effected free of charge.

Note:       We reserve the right to modify the design, construction and appearance of our products without advance notice.

ISMIL500 11/01





               The meter is supplied complete with a 9V battery. Slide off the battery compartment cover on the back of the meter. Install the battery while paying attention to its polarity.

               Always remove the electrode protective cap before taking any measurement. If the electrode has been left dry, soak the tip in storage solution for a few minutes to reactivate it.


Connect the ORP electrode to the BNC socket on the top of the meter.


Immerse the tip (2.5 cm) of the ORP electrode into the sample.


Turn the instrument on by pressing the ON/OFF key.


Allow the reading to stabilize before taking measurements.


After use, switch the meter off and store the electrode with a few drops of storage solution in the protective cap.


The meter is factory calibrated. ORP electrodes are inter-changeable and no mV calibration is needed when they are replaced.






              To correctly perfom a redox measurement, the surface of the Milwaukee ORP electrode must always be clean. Use for this purpose the M10000B rinse solution. If needed, brush the Platinum tip with very fine abrasive paper.

              When not in use, the tip of the electrode should always be kept moist and safe from any mechanical stress.




When the battery becomes weak the meter will display "S". When the low battery indicator appears, the battery has only about 50 hours of working time left. A low battery will result in

unreliable measurements. It is recommended to replace the battery immediately. Battery replacement must only take place in a non hazardous

area using an alkaline 9V battery. Turn the meter off, slide off the battery compartment cover at the rear of the meter and replace the 9V battery with a new one. Make sure the battery contacts are tight and secure, seat the battery in its compartment and insert the cover again.