Hanna GroLine Waterproof Hydroponic pH Tester HI98118

The Hanna GroLine HI98118 Waterproof Hydroponic pH Tester provides a convenient way to measure pH and temperature in nutrient solutions, irrigation water, growing-media leachate, and prepared soil slurries. Its slim pocket-sized design, large dual-level display, automatic temperature compensation, and simple two-button operation make it an excellent everyday meter for hydroponic gardens, greenhouses, aquaponic systems, and container-grown plants.

The HI98118 displays pH and temperature simultaneously. A renewable cloth junction helps maintain electrode response when nutrient residue or suspended material begins to obstruct the reference pathway.

Key Benefits

• Measures pH and temperature with one pocket-sized tester
• Designed for hydroponic nutrient solutions and greenhouse applications
• Waterproof construction for humid growing environments
• Automatic temperature compensation
• Large LCD displays pH and temperature simultaneously
• Automatic one- or two-point pH calibration
• Compatible with Hanna GroLine Quick Calibration Solution
• Renewable cloth junction helps clear clogs and extend electrode life
• Stability indicator identifies when a reading is ready
• Battery percentage displayed at startup
• Low-battery warning below approximately 10%
• Selectable automatic shutoff
• Simple two-button operation

Measurement Specifications

Parameter	Range	Resolution	Accuracy
pH	0.00 to 14.00 pH	0.01 pH	±0.2 pH
Temperature	0.0 to 50.0°C / 32.0 to 122.0°F	0.1°C / 0.1°F	±0.5°C / ±1°F

Designed for Hydroponics and Growing Media

The HI98118 is designed primarily for testing liquid samples, including:

• Hydroponic nutrient solutions
• Aquaponic water
• Irrigation water
• Fertilizer mixtures
• Reservoir samples
• Container-media leachate
• Prepared soil or growing-media slurries

The glass electrode should not be forced directly into dry or compacted soil. For growing-media testing, collect leachate using a pour-through method or prepare a soil-to-water slurry before taking the measurement.

Renewable Cloth Junction

The reference junction creates the electrical pathway required for pH measurement. Fertilizer residue, mineral buildup, and fine particles can eventually obstruct this pathway and cause slow, drifting, or unstable readings.

If conditioning, cleaning, and calibration do not correct an erratic response, approximately 3 mm or 1/8 inch of the cloth junction can be carefully pulled out and the contaminated portion trimmed away. Always leave at least 3 mm of cloth extending beyond the reference compartment.

Hanna states that the cloth junction can be renewed approximately nine times. Recalibrate the meter after renewing the junction.

Calibration Options

The HI98118 supports two calibration modes:

• Quick Cal: Automatic one-point calibration using Hanna GroLine Quick Calibration Solution at pH 6.86.
• Standard calibration: Automatic one- or two-point calibration using pH 4.01, 7.01, and 10.01 buffers.

For routine hydroponic measurements, calibrate with pH 7.01 followed by pH 4.01. These two standards bracket the mildly acidic range commonly used for hydroponic nutrient solutions.

Quick Cal provides a fast routine calibration, but Hanna recommends two-point calibration when improved accuracy is required.

How to Measure Nutrient-Solution pH

1. Remove the protective cap.
2. Rinse the electrode tip with purified water.
3. Immerse the bottom portion of the tester in the sample.
4. Gently stir to release trapped air and ensure even contact.
5. Wait for the stability indicator to disappear.
6. Read the pH on the primary display and temperature on the secondary display.
7. Rinse the electrode between samples to prevent cross-contamination.
8. Add storage solution to the protective cap and reinstall it after use.

Test a well-mixed sample away from concentrated nutrients, pH adjusters, dosing outlets, and freshly added supplements.

Testing Soil or Growing Media

The HI98118 should be used with a liquid extract rather than being pushed directly into the growing medium.

For a basic soil slurry:

1. Combine equal portions of soil or growing medium and distilled water.
2. Mix thoroughly.
3. Allow the mixture to rest so larger solids can settle.
4. Place the electrode into the liquid portion without forcing it into coarse material.
5. Wait for the reading to stabilize.

A pour-through leachate method can also be used with container-grown plants. For consistent comparisons, use the same sampling method, water source, resting time, and soil-to-water ratio each time.

Cleaning the Electrode

Clean the electrode whenever readings become slow, unstable, or difficult to calibrate.

For general residue:

1. Soak the electrode tip in Hanna General Purpose Cleaning Solution.
2. Rinse thoroughly with distilled or deionized water.
3. Soak the electrode in Hanna Storage Solution for at least one hour.
4. Recalibrate before taking measurements.

Dedicated cleaning solutions may be required for protein deposits, inorganic buildup, oil, or grease. Do not wipe or scrub the glass sensing bulb.

Proper Electrode Storage

The pH electrode must remain hydrated. Add several drops of Hanna Electrode Storage Solution to the sponge inside the protective cap before storing the tester.

If storage solution is temporarily unavailable, pH 4.01 or pH 7.01 buffer may be used. Never store the electrode in distilled, deionized, or reverse-osmosis water. Pure water can damage the reference system and shorten electrode life.

If the electrode dries out, soak the sensing tip in storage solution before calibrating. A short rehydration may restore a recently dried electrode, while an electrode shipped dry or stored dry for an extended period may require several hours of conditioning.

Calibration Best Practices

• Use fresh calibration buffer.
• Pour buffer into a separate clean container.
• Never return used buffer to its original container.
• Rinse the electrode between different buffers.
• Begin two-point calibration with pH 7.01.
• Use pH 4.01 as the second point for typical hydroponic applications.
• Recalibrate after cleaning or renewing the cloth junction.
• Calibrate more frequently when high accuracy is required.

Battery and Automatic Shutoff

The HI98118 operates on a replaceable CR2032 battery. The meter displays the remaining battery percentage during startup and provides a low-battery warning when power drops below approximately 10%.

Automatic shutoff can be set for:

• 8 minutes
• 60 minutes
• Disabled

The current Hanna product listing estimates approximately 1,000 hours of continuous battery operation.

What’s Included

• Hanna GroLine HI98118 pH and temperature tester
• Hanna GroLine Quick Calibration Solution sachets
• Electrode cleaning solution sachet
• Protective storage cap
• CR2032 battery
• Quality certificate
• Instruction manual

Recommended Accessories

For accurate readings and proper electrode care, pair the HI98118 with:

• Hanna GroLine Quick Calibration Solution
• Hanna GroLine pH 4.01 Calibration Buffer
• Hanna GroLine pH 7.01 Calibration Buffer
• Hanna General Purpose Cleaning Solution
• Hanna pH Probe Storage Solution
• Clean calibration and sample cups

Regular calibration, cleaning, and proper wet storage are essential for dependable pH measurements and long electrode life.