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DM-2: Commercial In-Line Dual TDS Monitor

DM-2: Commercial In-Line Dual TDS Monitor
DM-2 Installed The DM-2 can easily be installed on any water filtration system that removes TDS to show the TDS levels of both the feed and product water. 1/4" quick-connect T-fittings are standard. (3/8" and 1/2" are also available.)
Where to buy: Find a distributor in your region.

Install on industrial systems such as car washes, window washing, manufacturing, and food processing. UPGRADED APRIL 2012! The newly upgraded model features digital calibration, low battery indicator, improved accuracy, longer battery life (2 years), longer auto shut-off time (3 min), diagnostic error messaging, and shielded sensor cables. (Upgraded features below are in red.)

Instruction Manual


  • Highly efficient and accurate due to its advanced microprocessor technology.
  • Displays TDS levels of the Feed Water and Product Water with in & out electrode probes.
  • Auto-Off function conserves battery power. The unit shuts off automatically after 3 minutes.
  • Dual Range - Measures from 0-999 ppm, with a resolution of 1 ppm. From 1000 to 9990 ppm, the resolution is in 10 ppm increments, indicated by a blinking 'x10' image.
  • Factory Calibrated: our meters are calibrated with a 342 ppm NaCl solution. The DM-2 features digital calibration.
  • Diagnostic error messaging
  • Shielded sensor cables
  • Comes equipped with 1/4 inch Mur-lok® Quick-Connect T-fittings. Also available with 3/8" or 1/2" fittings.
  • Installs quickly and easily.

Differences from the DM-1:

  • Designed for commercial/industrial applications.
  • Stronger, water-resistant casing.
  • Digital calibration can be done individually on each line.
  • Improved design, including an extra large, easy-to-read LCD display.
  • Longer, waterproof, shielded cables.
  • Variable mounting bracket.


Range: 0-9990 ppm
Accuracy: ±2%
Conversion Factor: NaCl (avg. 0.5)
Cable Length: 46" (including sensor), shielded cables
Sensor: Dual, 1/4" diameter for quick-connect fittings (model SP-3, included)
Digital Calibration: Digitally factory calibrated to NaCl 342 ppm. Re-calibration can be done separately for each line.
Power source: 2 x AA batteries (included)
Battery life: Approx. 2 years 
Size: 11.6 x 6.8 x1.8 cm (4.6 x 2.6 x .7in.)
Weight: 201.3 g (7.1 oz.)



NOTE: All water purification and filtration systems are different.  Please contact the manufacturer of your RO or DI system to determine when you should change your filter cartridges or membranes (based on TDS levels and/or percent rejection). 

With a TDS monitor or meter, you can easily determine your RO system's performance by calculating the percent rejection. Once you have obtained the TDS levels of your feed water (IN) and product water (OUT), use the calculator below to determine the percent rejection of your RO system.
Enter the TDS level of the product water
Enter the TDS level of the feed water

Percent Rejection = %