HM Digital In-Line Dual TDS Monitor DM-1

SKU: AQU-TDS-DM1 Category:


Know your purity – both coming and going!

A TDS (Total Dissolved Solids) meter is critical for system maintenance and problem solving. If you have a problem, the first thing Aquasafe will ask is “what are the TDS readings?” The TDS meter is the only way check to confirm that the RO membrane is working properly and at what efficiency. It is also the only way that you can tell when the DI filter is exhausted. We strongly recommend buying PSI and TDS meters as they are absolutely essential in diagnosing problems, and confirming the system is operating as it was designed.

This is a genuine HM Digital meter. It is capable of measuring the ppm of your tap water coming into your R.O. system as well as the ppm of the purified water coming out of your R.O. membrane. This enables you to compare them any time and see when the filters are wearing out and need changing.


  • ‘Water in’ and ‘water out’ out electrode probes read TDS levels of the feed (tap) water and your purified R.O. water.
  • Sophisticated microprocessors insure accuracy
  • An Auto-off function shuts the meter off after 10 minutes to conserve battery life
  • Measurement Range: 0-9990 ppm. The display uses increments of 1ppm for the range 0-999 ppm, and increments of 10ppm for the range 1000 to 9990 ppm.
  • Factory Calibration: Calibrated with a 342 ppm NaCl solution. If necessary, you can re-calibrate your meter with a mini-screwdriver.
  • Quick and easy install. Mur-lok® Quick-Connect T-fittings make installation a breeze.


  • Range: 0-9990 ppm
  • Accuracy: ±2%
  • Conversion Factor: NaCl (avg. 0.5)
  • Cable Length: 24.5″ (including sensor)
  • Fittings: 1/4″ standard, also available with 3/8″ or 1/2″
  • Power source: 2 x 1.5V button cell batteries (LR44 or equivalent; included)
  • Battery life: approx. 1000 hours
  • Dimensions: 7.6 x 2 x 4.7 cm (3 x .8 x 1.9 in.)