Hanna GroLine Hydroponic Nutrient Monitor HI981420-01

The Hanna GroLine Hydroponic Nutrient Monitor HI981420-01 provides continuous, around-the-clock measurement of pH, electrical conductivity, TDS, and solution temperature. Designed for hydroponic reservoirs, aquaponic systems, greenhouses, fertigation tanks, and other controlled growing environments, it helps growers recognize changing root-zone conditions before they become larger crop problems.

The included HI1285-8 multiparameter probe combines pH, EC/TDS, and temperature sensors in one durable body. Measurements are automatically recorded every 15 minutes, while the large backlit display provides current readings, trend graphs, alarm notifications, and stored measurement history.

Key Benefits

• Continuous four-parameter monitoring: Tracks pH, EC, TDS, and nutrient-solution temperature from one probe.
• Automatic data logging: Records measurements every 15 minutes and stores up to 30 days of history.
• Trend identification: Displays minimum, maximum, and average measurements to help identify recurring changes.
• Selectable EC or TDS display: View nutrient concentration as mS/cm, 500-scale ppm, or 700-scale ppm.
• Quick Cal compatibility: Calibrates pH and conductivity simultaneously using Hanna Quick Cal solution.
• Traditional calibration options: Supports standard pH buffers and separate EC calibration solutions when preferred.
• High and low alarms: The display flashes when a monitored parameter moves outside the programmed range.
• Multiple display modes: Shows all essential readings together, cycles through individual parameters, or displays real-time graphs.
• USB-C data export: Transfers stored information to a compatible flash drive or computer in CSV format.
• Good Laboratory Practice data: Stores information from the five most recent pH and EC calibrations.
• Automatic temperature compensation: Adjusts pH and conductivity measurements for solution temperature.
• Electrical-noise resistance: The probe’s built-in preamplifier helps protect the pH signal from transient interference caused by pumps, ballasts, and other grow-room equipment.
• Plant-friendly display: Green backlighting provides clear visibility without an excessively bright grow-room display.
• Automatic dimming: An ambient light sensor adjusts the display backlight according to surrounding conditions.
• IP65-rated monitor enclosure: Resists dust and low-pressure water jets when properly installed.

Parameters Monitored

The HI981420-01 continuously measures four essential characteristics of a hydroponic nutrient solution:

• pH: Indicates whether the solution is within the desired acidity or alkalinity range for nutrient availability.
• Electrical Conductivity: Measures the solution’s ability to conduct electricity and provides an indication of dissolved ionic nutrient concentration.
• TDS: Converts the conductivity measurement into an estimated parts-per-million concentration using either a 0.5 or 0.7 conversion factor.
• Temperature: Helps growers monitor root-zone conditions and is used for automatic pH and EC temperature compensation.

This monitor measures the overall concentration of dissolved ionic material. It does not identify the concentration of individual elements such as nitrogen, phosphorus, potassium, calcium, or magnesium.

Measurement Specifications

• Monitor pH Range: 0.00–14.00 pH
• Included Probe pH Range: 0.00–13.00 pH
• pH Resolution: 0.01 pH
• pH Accuracy: ±0.05 pH at 77°F
• EC Range: 0.00–10.00 mS/cm
• EC Resolution: 0.01 mS/cm
• EC Accuracy: ±0.10 mS/cm from 0.00–5.00 mS/cm and ±0.20 mS/cm from 5.00–10.00 mS/cm
• 500-Scale TDS Range: 0–5,000 ppm
• 700-Scale TDS Range: 0–7,000 ppm
• TDS Resolution: 10 ppm
• TDS Accuracy: ±2% of full scale
• Monitor Temperature Range: 32–140°F, or 0–60°C
• Included Probe Temperature Range: 32–122°F, or 0–50°C
• Temperature Resolution: 0.1°F or 0.1°C
• Temperature Accuracy: ±1°F or ±0.5°C
• Temperature Compensation: Automatic
• EC Temperature Coefficient: 1.9% per °C
• Logging Interval: Every 15 minutes
• Stored History: Up to 30 days
• Connectivity: USB Type-C
• Power Supply: Included 12 VDC adapter with U.S. plug
• Monitor Enclosure: IP65
• Operating Environment: 32–122°F with up to 95% relative humidity, non-condensing

HI1285-8 Multiparameter Probe

The included HI1285-8 combines three sensors into one immersion-style probe:

• Preamplified pH electrode
• Renewable cloth reference junction
• Gel electrolyte
• Two graphite conductivity electrodes
• Integrated temperature sensor
• Polypropylene body
• DIN monitor connection
• Approximately 6.6-foot cable
• IP68 rating for continuous immersion up to approximately 6.6 feet
• Recommended for hydroponic, aquaponic, and greenhouse nutrient reservoirs

The solid-state preamplifier helps protect the pH measurement from transient electrical noise created by pumps, grow-light ballasts, and similar equipment.

This immersion probe is intended for use in tanks and reservoirs. Growers requiring a threaded probe for permanent pipe installation should consider the HI981421 model with its HI1285-9 inline probe.

Display and Data History

The large LCD can be configured to show:

• pH, EC or TDS, and temperature simultaneously
• Individual parameters in a repeating three-second cycle
• Real-time measurement graphs
• Stored historical graphs
• Minimum, maximum, and average readings
• High and low alarm messages
• Calibration information
• Current date and time

The monitor retains settings and operating parameters in nonvolatile memory. Programmed settings remain stored if power is temporarily interrupted, although continuous measurement and logging require the power adapter to remain connected.

Automatic Data Logging

Measurements are automatically recorded every 15 minutes for the previous 30 days. Stored data includes:

• pH
• EC
• TDS
• Temperature
• Minimum values
• Maximum values
• Average values
• Measurement and alarm status

Historical data can be reviewed directly on the monitor or exported through its USB-C connection. Exported CSV files can be opened with common spreadsheet software for reviewing trends, documenting crop cycles, or comparing reservoir performance.

The USB-C connection is intended for data transfer. It does not provide Wi-Fi, Bluetooth, cloud storage, app notifications, or remote internet monitoring.

Calibration Options

The HI981420-01 supports two calibration approaches.

Quick Cal Calibration

Hanna Quick Cal solution allows a simultaneous one-point calibration of pH and conductivity. This simplifies regular maintenance by placing the clean probe into one compatible calibration solution.

Standard pH Calibration

The pH sensor supports automatic one- or two-point calibration using:

• pH 4.01 buffer
• pH 7.01 buffer
• pH 10.01 buffer

Two-point calibration is recommended when greater confidence is needed across the expected operating range.

Standard EC Calibration

The conductivity sensor supports automatic one-point calibration using:

• 1.41 mS/cm conductivity standard
• 5.00 mS/cm conductivity standard

TDS calibration is completed through the EC calibration because the displayed ppm value is calculated from the conductivity measurement and selected conversion factor.

GLP Calibration Records

The Good Laboratory Practice feature stores data from the five most recent pH and EC calibrations. This helps growers confirm when the probe was calibrated and identify maintenance patterns that could affect measurement reliability.

Understanding the TDS Scales

The monitor offers two selectable conductivity-to-TDS conversion factors:

• 500 ppm scale: Uses a 0.5 conversion factor
• 700 ppm scale: Uses a 0.7 conversion factor

For example, an EC measurement of 2.0 mS/cm corresponds to approximately:

• 1,000 ppm on the 500 scale
• 1,400 ppm on the 700 scale

Select the scale used by the applicable fertilizer manufacturer, feeding chart, or previous meter. Switching conversion factors changes the displayed ppm number but does not change the actual conductivity of the solution.

High and Low Alarms

Growers can establish individual high and low alarm limits for:

• pH
• EC or TDS
• Temperature

When a measurement moves outside the selected range, the monitor flashes its display and presents an alarm message. Each parameter’s alarms can be enabled or disabled separately.

These alarms are displayed locally on the monitor. The HI981420-01 does not automatically add nutrients, adjust pH, activate external dosing equipment, or send remote notifications.

Installation Guidelines

1. Mount the monitor vertically at eye level on a stable, vibration-free wall.
2. Position it within reach of the probe cable and an appropriate power outlet.
3. Keep the monitor away from direct sunlight, continuous dripping, condensation, and excessive heat.
4. Connect the HI1285-8 probe while the monitor is powered off.
5. Remove the probe’s protective storage cap.
6. Rinse away any storage solution before calibration or reservoir installation.
7. Calibrate the pH and conductivity sensors.
8. Place the probe where it remains continuously immersed.
9. Choose a location with representative circulation and minimal air bubbles.
10. Keep the probe away from concentrated nutrient or pH-adjuster injection points.
11. Configure the measurement units, TDS scale, alarm limits, date, time, and display preferences.

Do not place the monitor enclosure in the reservoir. The IP65 enclosure resists dust and low-pressure water jets, but it is not submersible. Only the properly connected HI1285-8 probe is intended for continuous immersion.

Probe Care and Maintenance

• Rinse the complete probe with clean water approximately once per week.
• Inspect the pH bulb, cloth junction, and graphite EC sensors for accumulated fertilizer residue.
• Clean the probe with Hanna HI700661 agricultural electrode cleaning solution when deposits are present.
• After cleaning, soak the probe in Hanna HI70300 electrode storage solution for approximately one hour.
• Rinse away storage solution before calibration because it is highly conductive.
• Recalibrate after cleaning.
• Keep the pH bulb and reference junction moist.
• Never store the pH electrode in distilled, deionized, or reverse-osmosis water.
• Prevent concentrated fertilizer, pH adjusters, or undiluted additives from contacting the probe.
• Replace the probe when it can no longer maintain calibration after proper cleaning and conditioning.

What Is Included

• Hanna GroLine HI981420 monitor
• HI1285-8 pH, EC/TDS, and temperature probe
• Two Hanna Quick Cal solution sachets
• Two agricultural electrode cleaning solution sachets
• 12 VDC power adapter with U.S. plug
• Quick-start guide
• Instruction manual
• Monitor quality certificate
• Probe quality certificate

Important Usage Notes

• This product monitors nutrient-solution conditions but does not perform automatic dosing.
• The monitor does not include Wi-Fi, Bluetooth, cloud connectivity, or remote alerts.
• Use the correct 500 or 700 ppm conversion factor when comparing readings with a feeding chart.
• Keep the probe continuously immersed during monitoring.
• Install the probe where the sample represents the overall reservoir rather than a freshly dosed area.
• Keep the pH sensor hydrated with proper electrode storage solution.
• Calibrate regularly and whenever readings appear questionable.
• Follow Hanna’s current instructions for installation, calibration, cleaning, storage, and probe replacement.