HI98131 Combo Tester is waterproof and measures pH/EC/PPM/Temp.  This pocket sized tester does everything that the HI9814 Combo Meter can do.


  • All measurements in a single, hassle-free tester.
  • Quick Cal combo solution calibrates pH and conductivity all at once with a single solution.
  • Easily replaceable pH electrode  
  • Simplified menu compared to the past black combo pen (HI98129)

    • 3 sensors in a single meter
    pH electrode with extractable junctionExposed temperature probe for faster EC/TDS readings
    • Waterproof
    Designed to withstand the harsh grow room environments. 
    • Wide pH Range
    pH range is from 0.00 to 14.00 pH
    • Selectable EC to TDS conversion factor
    Choice of either a 0.5 or 0.7 conversion factor0.7 (700 CF) conversion factor is for an EC reading of 1.00 mS/cm = 700 ppm
    • Automatic Temperature Compensation
    All readings are compensated for variations in temperature
    • Stability indicator
    Meter displays a clock tag that will disappear when the reading has achieved stability
    • HOLD button
    Freezes reading on the display to allow recording of measurement
    • BEPS (Battery Error Prevention System
    Meter will automatically shut off if there is not enough power to get an accurate measurement
    • Battery % level at startup
    • Low Battery Indicator

    pH Range

    0.00 to 14.00 pH

    pH Resolution

    0.01 pH

    pH Accuracy

    ±0.1 pH

    pH Calibration

    automatic, at one or two points using standard buffers (pH 4.01, 7.01,10.01); one point calibration using quick calibration solution

    Conductivity Range

    0.00 to 6.00 mS/cm

    Conductivity Resolution

    0.01 mS/cm

    Conductivity Accuracy

    ±2% F.S.

    TDS Range

    0 to 3000 ppm (500 CF); 0 to 3999 ppm (700 CF)

    TDS Resolution

    10 ppm (mg/L)

    TDS Accuracy

    ±2% F.S.

    Temperature Range

    0.0 to 60.0°C / 32.0 to 140.0°F

    Temperature Resolution

    0.1°C / 0.1°F

    Temperature Accuracy

    ±0.5°C /±1°F

    Temperature Compensation

    pH: automatic; EC/TDS: automatic with β set at 1.9%/°C

    EC/TDS Calibration

    automatic, one-point at 1.41 mS/cm or 5.00 mS/cm; one point calibration using quick calibration solution

    TDS Conversion Factor

    0.5 (500 ppm) or 0.7 (700 ppm)

    Battery Type/Life

    1.5V (4) / approx. 100 hours of continuous use, auto-off after 8 minutes of non-use


    after 8 minutes, 60 minutes, disabled


    0 to 50°C (32 to 122°F); RH max 100%


    163 x 40 x 26 mm (6.4 x 1.6 x 1.0’’)


    100 g (3.5 oz.)

    Ordering Information

    HI98131 is supplied with HI73127 pH electrode, HI73128 electrode removal tool, batteries (4), instructions and quality certificate.

    • Auto-off - Selectable time before meter will automatically shuts off to conserve battery life. Options are after 8 minutes, 60 minutes , or disabled.
  • When the level is below 5%, the  battery symbol on the LCD blinks to indicate a low battery condition.
  • Temperature displayed in oC or oF along with pH, EC or TDS reading
  • 0.5 (500 CF) conversion factor is for an EC reading of 1.00 mS/cm = 500 ppm

  • Amperometric EC/TDS sensor

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