HM Digital Waterproof EC / TDS / Temp Combo Meter

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HM Digital, Inc.

COM-100: Waterproof EC / TDS / Temp Combo Meter

  • Ideal for all water quality testing, water purification applications, wastewater regulation, aquaculture, hydroponics, colloidal silver, labs & scientific testing, pools & spas, ecology testing, boilers & cooling towers, water treatment and more.
  • Measures electrical conductivity (EC), total dissolved solids (TDS) and temperature.
  • Three different calibration options (KCl, 442TM, NaCl), each with its own non-linear conversion factor.
  • Automatic Temperature Compensation (ATC) using three temperature coefficients
  • Waterproof housing (IP-67 rating)
  • Measurement Range: 0-9990 µS; 0-8560 ppm (auto-ranging)
  • Digital Calibration (push button)
  • Auto-off function, data-hold function and low-battery indicator
  • Display: large and easy-to-read LCD screen includes simultaneous temperature reading.
  • Replaceable Sensor (model SP-C1)
  • Factory Calibrated: The COM-100 meter is calibrated with a 1413 µS solution. The meter can be recalibrated with digital calibration using the push buttons, rather than a screwdriver.
  • Includes a cap, batteries and lanyard.
  • EC Range: 0 - 9990 µS
  • TDS Range: 0-8560 ppm (mg/L)
  • Temperature Range: 0-80 °C; 32-176 °F
  • Resolution: 0-99: 0.1 µS/ppm; 100-999: 1 µS/ppm; 1000-9990: 10 µS/ppm. Temp. resolution is 0.1 °C/F
  • Accuracy: +/- 2%
  • EC to TDS Conversion Factor: Non-linear conversions for KCl, 442TM or NaCl solutions, set by the user.
  • Calibration: Digital calibration by push button.
  • Probe: Detachable platinum electrodes
  • Housing: IP-67 Waterproof (submersible; floats)
  • Power source: 3 x 1.5V button cell batteries (included) (model 357A)
  • Dimensions: 18.5 x 3.4 x 3.4 cm (7.3 x 1.3 x 1.3 inches)
  • Weight: 90.7g (3.2 oz)

Product Manuals & Documentation

HM Digital Waterproof EC / TDS / Temp Combo Meter

Owner's Manual available for download in Adobe PDF file format

Manufacturer Info

HM Digital, Inc.
Established in 1987, HM Digital, Inc. (formerly known as Heemang Electronics) is an original equipment manufacturer (OEM) that has been recognized worldwide for providing the best values in water testing instrumentation, especially the increasingly popular TDS meter.

Forsaken77 from Long Island, NY UNITED STATES


Experience Level: Intermediate

Best Handheld TDS/EC/TEMP

I've had a few different HM Digital handheld TDS checkers over the years. This is by FAR the best one. Not only does it check for Electrical Current (EC), it has a Fahrenheit Thermometer and has digital calibration, so no more turning screws with a micro-screwdriver to calibrate, as well as ppm & ppt in multiple formats (NaCl, 4-4-2, ect...). Another great aspect is that it's WATERPROOF and floats! You don't know how many of these I've accidentally dropped into the tank, sump or RODI reservoir. HM Digital also makes most of the inline TDS monitors for RODI systems. I would stay away from Hanna, but HM Digital is solid, in my opinion. Whichever device you go with, make sure you pick up the HM 342 NaCl Calibration Fluid for it. Good Luck with your tanks & Happy Holidays (written in December)

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