HM Digital Testing Equipment
HM Digital® water quality testing instruments are superior in construction and 
performance, yet made available at a very economic cost. HM Digital, Inc.® is the only 
manufacturer of economical in-line dual TDS meters that measure total dissolved solids 
(TDS) levels of feed and product water lines simultaneously, an effective way to compare 
rejection rates and gauge reverse osmosis membrane, water fi lter and water purifi cation 
performance. 
Testing Equipment
TDS METER
Description: TDS & TEMP
METER W/ CASE;0-9990
PART# TDS-3
PRICE: $19.99
Description: ECONOMY TDS
 METER; 0-9999 PPM 
PART#TDS-EZ
PRICE: $19.99 
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.
IN-LINE D TDS METER




















































Description: POCKET SIZE TDS 
METER; 0-999 PPM (W/ATC) 
PART#TDS-4
PRICE: $21.99

HM TDS-4 Meter will monitor the TDS levels for drinking water, water filters, hydroponics, Aquariums, Food and Coffee, Pools and Spas and residential RO applications. Measurement range is 0-9990 ppm.


TDS Meters Are Used To:


    * Check the performance of your water filter

    * Confirm your drinking water is at a safe, healthy TDS level

    * Measure TDS (Total Dissolved Solids) levels for other applications


The HM TDS4 also features:


    * Hold Function -- so you can save measurements for convenient reading and recording

    * Auto-Off Function -- Shuts the meter off automatically after 10 minutes to conserve batteries

    * Automatic Temperature Compensation (ATC)

    * Smallest & Lightest TDS meter on the market

    * 1000+ Hours of Continuous Use

    * 3 Year Limited Warranty


TDS4 Meter Specifications:


    * TDS Range: 0-9990 ppm (parts per million)

    * Temp Range: 0-80 degrees Celsius

    * Resolution: 1 ppm, 1 degree Celsius

    * Accuracy: plus or minus 2%

    * Power Source: 2 x 1.5 volt button cell batteries (included)

    * Battery life : 1000 hours

    * Dimensions: 5.5" x .9" x .55"
Description: EC/TDS/TEMP WATERPROOF METER 
PART# COM-100
PRICE: $77.99

FEATURES

  • 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.
  • See how the COM-100 stacks up against the competition.
  • Need help deciding which meter is right for you?  View ourTDS/EC Meter Selection Guide. 

SPECIFICATIONS

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) 
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)