GroLine Waterproof EC/TDS (ppm) Tester

The GroLine Waterproof EC/TDS (ppm) Tester (model HI98318) is a pocket-sized meter designed for measuring electrical conductivity and total dissolved solids in hydroponic nutrient solutions. At only 0.7 inches thick, it fits comfortably in one hand, and its large LCD display simultaneously shows EC or TDS readings alongside temperature. All functions are controlled with just two buttons, making it straightforward to operate at any stage of your grow.

GroLine Waterproof EC/TDS (ppm) Tester Specifications

The HI98318 is built around a graphite sensor that reduces polarization effects, a common source of measurement drift in EC meters used in mineral-rich hydroponic solutions. Key technical details are listed below.

Why Choose the GroLine Waterproof EC/TDS (ppm) Tester

EC and TDS monitoring is a daily task in hydroponic growing. The meter you reach for should give you a fast, reliable reading without adding friction to your workflow. The HI98318 is designed with that routine use in mind.

• Graphite sensor reduces polarization drift. Conventional stainless-steel EC probes can accumulate polarization effects over repeated measurements in mineral-rich nutrient solutions. The graphite sensor in the HI98318 is less susceptible to this effect, supporting more consistent readings over time.
• Slim, ergonomic form factor. At 0.7 inches thick, this meter is genuinely pocket-sized. It fits in the same shirt pocket as a pen, which matters when you’re moving between reservoirs and doing spot checks throughout the day.
• Large LCD with simultaneous readouts. The display shows EC or TDS and temperature at the same time, along with calibration status, reading stability confirmation, and a low battery indicator. You can see everything relevant in a single glance.
• Two-button operation. One button turns the meter on and off; the other initiates automatic one-point calibration. There are no menus to navigate and no settings to accidentally change mid-measurement.
• Quick calibration with standard solution. The HI98318 supports fast calibration using Hanna pH/EC Quick Cal Solution, keeping the process simple and compatible with a widely available calibration standard.
• Waterproof construction. The meter is built to withstand the wet conditions typical of hydroponic environments, including splashes from reservoirs and recirculating systems.

Best Uses for the GroLine Waterproof EC/TDS (ppm) Tester

This meter is suited to growers who take daily or weekly nutrient solution readings and need a reliable handheld instrument for the task. Below are the primary use scenarios where the HI98318 fits well.

• Hydroponic reservoir management. Monitoring EC and TDS in a recirculating or drain-to-waste hydroponic system is the primary design target. The meter handles frequent dip-and-read checks in DWC buckets, NFT channels, or flood-and-drain trays.
• Nutrient solution mixing. When preparing nutrient mixes from concentrates, confirming the final EC against a target range is straightforward with the HI98318. The stability indicator tells you when the reading has settled so you’re not recording a mid-swing value.
• Water quality baseline checks. Before mixing nutrients, measuring the EC of source water (RO, tap, or well) helps establish the baseline. This is especially relevant when using an reverse osmosis filtration system, where you want to confirm the filtered water is near zero EC before adding nutrients.
• Spot checks across multiple systems. For growers running several reservoirs or cultivation zones, a slim pocket meter is easier to carry and clean between measurements than a benchtop unit. The waterproof body handles the quick rinse between samples.
• Educational and introductory use. The two-button design and immediate readout make this meter accessible for growers learning to manage nutrient programs. The calibration indicator removes guesswork about whether the meter is ready to use.

Compatibility

The HI98318 measures electrical conductivity and total dissolved solids in liquid solutions. It is designed for use with hydroponic nutrient solutions but is also suitable for any water-based solution where EC or TDS monitoring is relevant.

Calibration solutions: The meter uses Hanna pH/EC Quick Cal Solution for one-point calibration. Using the correct calibration standard is important for accuracy; other EC calibration solutions may be compatible but should be verified against the manufacturer’s guidance.

System compatibility: The meter works independently of any specific hydroponic system type. It is appropriate for DWC (deep water culture), NFT (nutrient film technique), drip, ebb and flow, and coco or media-based systems where solution EC is monitored in the reservoir or runoff. If you are also monitoring pH in your system, pairing the HI98318 with a calibrated pH pen or an EC calibration kit covers both critical solution parameters.

Electrode and accessory notes: The HI98318 is a complete instrument. For growers who need a replacement or upgrade electrode for a different meter in their toolkit, the replacement EC electrode options available for compatible meters may be relevant to consider alongside this tester.

Usage Guidelines

For reliable EC and TDS readings, follow a consistent measurement procedure. The steps below reflect the two-button operation and calibration approach described in the product documentation.

1. Calibrate before first use and periodically thereafter. Press the calibration button with the probe submerged in fresh Hanna pH/EC Quick Cal Solution. Wait for the stability indicator to confirm a settled reading, then complete the calibration. Calibration frequency depends on use intensity; daily calibration is common practice in production environments.
2. Rinse the probe with clean water before each measurement. Cross-contamination between samples can affect accuracy. A brief rinse with deionized or RO water and a soft wipe removes residual solution from the previous reading.
3. Submerge the probe to the recommended depth. Ensure the graphite sensor is fully immersed in the sample. Partial submersion or air bubbles at the sensor surface will produce inconsistent readings.
4. Wait for the stability indicator. The LCD shows a stability indicator when the reading has settled. Record the value only after this indicator confirms a stable measurement.
5. Read both EC/TDS and temperature. The display shows temperature alongside EC or TDS. Temperature affects EC readings, so noting temperature along with the EC value is useful when comparing measurements taken at different times or in different locations.
6. Rinse and dry after use. After completing measurements, rinse the probe with clean water and allow the meter to air dry or wipe dry before storing. Do not store with the probe immersed in solution.

Target EC ranges vary by crop type, growth stage, and nutrient program. Refer to your nutrient manufacturer’s feed chart for recommended EC values at each stage of growth.

Sources & Further Reading