pH-80S Usage, Calibration & Care Guide

pH-80S Usage, Calibration & Care Guide

Whether you're working in hydroponics, maintaining an aquarium, or testing RO water, the HM Digital PH-80 is a compact, easy-to-use digital pH meter for everyday water testing.

Designed for quick and convenient measurements, the PH-80 helps you monitor pH levels in a range of water-testing applications.

Getting Started: Preparing the Meter

Your PH-80 comes with:

  • Small mylar packet of electrode storage solution
  • Large mylar packet of pH 7.0 buffer solution
  • Pre-installed LR44 batteries
  • Sponge inside the cap for moisture retention

Step 1: Wet the Sensor

Pour enough electrode storage solution into the cap to moisten the sponge. Place the meter back into the cap and leave it standing upright for 15 minutes.

HM Digital PH-80 electrode storage solution preparation

Step 2: Prepare the Buffer Solution

Mix the large pH 7.0 buffer solution packet with 100 ml of distilled water. Keep the prepared solution sealed when not in use.

Preparing pH 7.0 buffer solution for HM Digital PH-80

How to Take pH Measurements

How to Take pH Measurements

  1. Remove the cap. Do not use the cap during testing.
  2. Press the POWER button. The display will briefly show "PH" and then display the current reading.

    3. Turning on the HM Digital PH-80 pH meter

  3. Dip the sensor into the water or liquid being tested.
  4. Swirl gently to help eliminate air bubbles around the sensor.
  5. Wait up to 30 seconds for the reading to stabilize.

    6. Taking a pH measurement with the HM Digital PH-80

  6. Press HOLD to freeze the reading on the display if required.
  7. Press POWER to turn the meter off.

    8. Using the HOLD function on the HM Digital PH-80

  8. Rinse the sensor with distilled, RO, or DI water and replace the cap for storage.

    9. Rinsing the HM Digital PH-80 sensor after use

Note: When testing very low-conductivity or ultra-pure water, readings can take longer to stabilize. Gently swirl the meter continuously or test in flowing water as appropriate for the application.

pH Calibration Instructions

Regular calibration helps maintain measurement accuracy. For routine use, calibrate the PH-80 regularly and whenever the meter's accuracy is in doubt.

The PH-80 supports automatic calibration using pH 4.0, pH 7.0, and pH 10.0 buffer solutions.

Calibration Steps

  1. Turn on the meter.
  2. Place the sensor into the appropriate buffer solution.
  3. If the displayed value needs adjustment, press and hold CAL for approximately 10 seconds until the display flashes.

Starting pH calibration on the HM Digital PH-80

  1. Use the UP/DOWN arrows to select the correct buffer value.
  2. Press ENTER.
  3. Wait while the display shows "CAL" and the calibration progress.
  4. When "End" appears, calibration is complete.

Completed pH calibration on the HM Digital PH-80

Changing the Batteries

When the battery icon flashes, replace the batteries.

  1. Pull out the orange battery compartment.
  2. Remove the three LR44 batteries.
  3. Insert the new batteries according to the polarity markings. The flat side is the positive terminal.
  4. Close the battery compartment securely.

Replacing the LR44 batteries in the HM Digital PH-80

Temperature Calibration (Advanced)

Advanced function: Temperature calibration is an advanced function and should only be performed when comparing the meter against a verified reference thermometer.
  1. With the meter off, press and hold POWER + TEMP for 5 seconds.
  2. "CAL" and the temperature value will flash.
  3. Use the UP/DOWN buttons to adjust the temperature to the verified reference value.
  4. Press ENTER to save the setting.
  5. "CAL" will flash and then "End" will appear.

Temperature calibration on the HM Digital PH-80

Common Issues and Troubleshooting

Issue Indicator Solution
Sensor is damaged or worn ⚠ The meter may require replacement.
Water has very low conductivity ⚠ Gently swirl the meter continuously or test in flowing water to help stabilize the reading.
pH is outside the meter's operating range — The PH-80 is designed for pH measurements from 0.0 to 14.0.
Internal error Err Refer to the user manual. If the error persists, the meter may require replacement.
Calibration will not complete — Check that the buffer solution is fresh and correctly prepared. Recalibrate using the appropriate buffer solution.
Temperature out of range Err Ensure the test liquid is within the meter's specified temperature range.

Care, Maintenance & Tips

  • Calibrate the meter regularly to maintain reliable readings.
  • Always store the meter with the cap securely fitted and the sponge properly moistened with electrode storage solution.
  • Never touch or scratch the glass electrode.
  • Rinse the sensor with distilled, RO, or DI water after use.
  • Clean any salt deposits from the cap when necessary.
  • Use only the recommended electrode storage solution for storing the sensor.

Advanced Reset Tip

If readings become inconsistent after repeated calibration cycles, reset the meter before recalibrating.

  1. Turn on the meter and hold HOLD for 10 seconds.
  2. "End" will appear briefly.
  3. Recalibrate the meter using a fresh pH 7.0 buffer solution.

Looking for the HM Digital PH-80 in India?

Octosquare is an importer and distributor of HM Digital products in India, supplying genuine HM Digital water-testing instruments and accessories.

HM Digital PH-80

A compact digital pH meter for quick and convenient water testing.

View PH-80