The HI981420-01 GroLine Monitor automatically records pH/EC/PPM/Temp data for 30 days and provides around-the-clock, continuous monitoring with user set-able alarms.

Quick to setup, simple to use, this monitor was designed with the grower in mind. Make your reservoirs easy to manage with the GroLine Monitor.

  • Trusted - 24/7 pH/EC/PPM/TEMP readings with user set high & low alarms.
  • Simple - Rugged combo probe designed for reservoirs.  
  • Simple - Convenient combo solution to calibrate pH/EC/PPM at once. 
  • Accountability - See the real data behind each calibration with GLP.  
  • Professional - Data logging records min, max, and average values automatically. 
  • Accurate - ±0.05 pH Accuracy.
  • Range - Highest EC/PPM range of any monitor in the market. 



  • 3 sensors combined in a single rugged probe body: pH electrode with renewable cloth junction, amperometric EC/TDS sensor, and an internal temperature sensor for temperature compensated readings
  • IP65 rated enclosure: designed to withstand harsh grow environments
  • Wide pH Range: measure pH from 0.00 to 14.00 pH
  • Selectable EC to TDS/ppm conversion factor: choice of either a 0.5 or 0.7 conversion factor
  • Automatic Temperature Compensation: all readings are compensated for variations in temperature, temperature displayed in oC or oF along with pH, EC or TDS reading
  • Large LCD with plant-friendly green backlighting: LCD can display all three essential hydroponic nutrient measurements at one time, a 3-second cycle of single measurements, or a real-time graph screen with options for measurement selection and log recall
  • Data logging for 30 days: logs every 15 minutes for last 30 days, stores min, max, and average values
  • Data transfer: USB-C port for easy data transfer to memory stick or PC
  • High and low alarms: warns when your nutrient solution is out of desired range by flashing display and message
  • Ambient light sensor: While HI981420 has the correct PAR values to be safe in photo sensitive gardens, auto dimming was added to the monitor as an added safety precaution. 


pH Range

0.00 to 14.00 pH

pH Resolution

0.01 pH, (0.1 pH)

pH Accuracy

±0.05 pH, (± 0.1 pH)

pH Calibration

one or two-point calibration (using pH 4.01,7.01, 10.01 buffers) using auto buffer recognition; one-point calibration using quick calibration solution

Temperature Compensation

automatic (0.0 to 60.0ºC/ 32.0 to 140.0°)


EC Range

0.00 to 10.00 mS/cm

EC Resolution

0.01 mS/cm

EC Accuracy

±0.1mS/cm (0.00 to 5.00mS/cm); ±0.2mS/cm (5.00 to 10.00mS/cm)

EC Calibration

one-point at 1.41 mS/cm or 5.00 mS/cm using auto standard recognition; one-point calibration using quick calibration solution

EC/TDS Temperature Compensation

automatic with β set at 1.9%/°C

TDS Range

0 to 5000 ppm (TDS conversion factor 0.5 (500 CF)); 0 to 7000 ppm (TDS conversion factor 0.7 (700 CF))

TDS Resolution

10 ppm

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



128 x 64 pixel B/W LCD with green backlight


USB Type-C

IP Rating



High and Low with enable/disable option for all parameters

Log Feature

Automatic logging for last 30 days at 15 minute interval


Good Laboratory Practice with last 5 pH and EC calibration history


HI1285-8 pH/EC/TDS/temperature polypropylene body, pre-amplified multiparameter probe with internal temperature sensor DIN connector and 2 m (6.6’) cable

Power Supply

12VDC adapter (included)


-5 to 50°C (23 to 122°F); RH max 95% non-condensing


125 x 185 x 38 mm (4.92 x 7.28 x 1.49”)


333g ( 11.7oz.)

Ordering Information

HI981420 is supplied with: HI1285-8 multiparameter probe, HI50036-0 Quick Cal buffer solution sachet (2), HI700661P Electrode cleaning solution sachets for agriculture (2), 12VDC adapter, instruction manual, Monitor Quality Certificate, & Probe Quality Certificate.

Warranty 2 Years 


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