GroStar GS3 EC Pen

Stop Guessing at Nutrient Strength — Read It Directly

Mixing feed by feel or by the label alone leaves room for under- or over-feeding — both of which show up later as stress symptoms that are far more annoying to diagnose than to prevent in the first place.

The GroStar GS3 takes the guesswork out by reading conductivity directly. Its titanium-alloy sensor is purpose-built for high-accuracy EC measurement, reporting EC, PPM (500 scale), PPM (700 scale), and temperature so you can match your numbers to whatever scale your nutrient program uses.

Like the rest of the GroStar lineup, it's built for the long haul: a replaceable probe means a worn sensor doesn't retire the whole pen, the IP67 rating shrugs off splashes, and a large backlit screen keeps your readings legible at a glance.

Key Features & Benefits

• Measures EC, PPM (500), PPM (700), and temperature — covers every conductivity scale your nutrient program might reference, all from one reading.
• Titanium-alloy sensor — is engineered specifically for high-accuracy EC measurement, holding up to repeated use in nutrient solution.
• Replaceable probe — lets you swap in a fresh sensor (GS3-E) rather than replacing the entire instrument when it reaches end of life.
• Large 3-color backlit screen — delivers clear, easy-to-read information whether you're checking levels in bright daylight or a dim grow room.
• IP67 waterproof rating — holds up to the splashes and spills that come with regular reservoir and feed-tank checks.
• Calibration solution included — ships with a 2.77 EC calibration solution (50ml) plus a 2-year instrument warranty and 1-year probe warranty.

Who Should Use the GroStar GS3

The GS3 suits growers who want to dial in nutrient strength precisely — rather than estimate it — and who'd rather read EC, PPM (500), and PPM (700) directly than convert between scales by hand.

EC, PPM (500), or PPM (700) — Why It Reads All Three

Different nutrient brands and regions reference conductivity differently — some in EC, others in PPM on a 500 or 700 scale — which can turn a simple feeding-strength check into a unit-conversion exercise. The GS3 reports all three from the same measurement, so you can match your reading to whatever scale your feeding chart uses without doing the math yourself.

Frequently Asked Questions

What does the GS3 measure?

It measures conductivity in EC, PPM on the 500 scale, PPM on the 700 scale, and temperature — all from a single reading, with automatic temperature compensation.

Why does it report three different conductivity scales?

Nutrient programs reference EC, PPM (500), and PPM (700) differently depending on the brand or region — reporting all three lets you match your reading to your feeding chart without converting by hand.

Can I replace the probe?

Yes — it uses a replaceable probe (GS3-E) built around a titanium-alloy sensor, so a worn sensor doesn't mean replacing the whole pen.

What calibration solution does it include?

It ships with a 2.77 EC calibration solution (50ml bottle), which you'll use to verify and adjust accuracy before each measuring session.

Is it waterproof?

Yes — it carries an IP67 waterproof rating and runs on AAA batteries with an auto-off function.