Hanna GroLine Hydroponic Waterproof Pocket pH/EC/TDS/Temperature Tester

The Hanna GroLine HI98131 is a slim, waterproof pocket tester that measures pH, electrical conductivity (EC), total dissolved solids (TDS in ppm), and temperature from a single device. Designed for hydroponics, greenhouse, and agricultural water management, it replaces four separate instruments with one two-button meter that fits in a shirt pocket.

HI98131 Specifications

All specifications below are sourced from the canonical product data and manufacturer documentation for the HI98131.

Why Choose the Hanna GroLine HI98131

The HI98131 consolidates four separate measurement tasks into a single pocket-sized instrument, which reduces the number of tools you need to carry into a grow room or greenhouse. Here is what sets it apart from basic single-parameter testers:

• Four measurements, one device. pH, EC, TDS, and temperature are all displayed without switching instruments or recalibrating between parameters. For growers who monitor nutrient solution regularly, this reduces time and the chance of calibration drift between readings.
• Quick Cal calibration. The HI98131 uses Hanna’s Quick Cal solution, which calibrates both pH and conductivity at the same time from a single standard. This shortens the daily calibration routine compared to meters that require separate pH buffer and EC standard solutions.
• Selectable TDS conversion factor. The EC-to-TDS multiplier can be set to 0.5 (giving a 500 ppm scale) or 0.7 (700 ppm scale). This matters because different nutrient manufacturers reference different conversion factors on their feed charts. Being able to match the scale to your brand’s chart avoids systematic under- or over-feeding errors.
• Waterproof construction. The housing is rated waterproof, which is practical in wet environments like NFT channels, flood-and-drain tables, or outdoor reservoirs where splash contact is routine.
• Slim, two-button interface. The minimal control layout means less to learn and fewer accidental mode changes during testing.

Best Uses for the Hanna GroLine HI98131

The HI98131 is suited to applications where fast, portable multi-parameter testing is more practical than a bench-top meter setup. Common use cases include:

• Hydroponic reservoirs. Checking nutrient solution pH, EC, and TDS before and after topping off or mixing fresh solution. The TDS conversion factor selection is particularly useful here because different hydro nutrient lines use different ppm scales.
• Greenhouse irrigation water. Verifying source water quality and nutrient EC at the irrigation manifold before it reaches the crop. If you are running an RO filtration system, the HI98131 can confirm permeate TDS is within target before nutrient mixing.
• Soil and soilless grows requiring pH monitoring. Growers running coco coir, perlite, or rockwool systems who spot-check runoff pH will find the single-device format reduces workflow steps.
• Agriculture and field use. The waterproof build and pocket size make it practical for field water testing, irrigation line checks, and fertigation monitoring in outdoor settings.
• Calibration verification. The Quick Cal system makes it straightforward to confirm the meter is reading accurately at the start of each grow day, which is good practice for any pH-critical crop.

Compatibility

The HI98131 is a standalone, battery-powered pocket tester and does not require a separate controller, hub, or software to operate. It is compatible with any nutrient solution, tap water, or irrigation water source. The selectable TDS conversion factor (0.5 or 0.7) makes it compatible with nutrient programs published on either the 500 ppm or 700 ppm scale.

For EC accuracy verification, you can use a traceable conductivity calibration standard such as the Apera GroStar EC calibration kit to cross-check readings if you suspect electrode drift. The HI98131’s Quick Cal solution handles routine daily calibration, while a secondary reference standard provides an independent check when precision is critical.

The meter is designed for aqueous solutions at typical hydroponic operating temperatures. It is not intended for measuring dry substrate, nutrient concentrates undiluted, or solutions outside the intended operating range specified in the manufacturer documentation.

Sources & Further Reading