Bluelab OnePen

Three Readings From One Waterproof Pen, pH + EC + Temp

Checking pH and nutrient strength usually means juggling two meters and writing numbers down by hand. The OnePen measures pH, conductivity (EC) and temperature at the same time and shows pH and EC together on a backlit display. Connect it to the Edenic app over Bluetooth to view, share and store readings instead of keeping a paper log.

One pen covers the daily reservoir check for a home grow and the spot checks a commercial team runs across many tanks. Conductivity reads in EC, mS/cm, CF, ppm 500 (TDS) or ppm 700, so it matches the nutrient chart you already follow.

Key Features & Benefits

• 0.01 pH resolution — reads pH 0.0–14.0 with ±0.05 accuracy at 25°C / 77°F for fine pH adjustments.
• Replaceable probe — the double-junction pH probe and titanium EC electrodes swap out as one replacement probe (PROBONE), so a worn sensor does not mean a new pen.
• IP68 rated — dust and waterproof, built for wet reservoir work.
• Edenic app connection — Bluetooth sends measurements to your phone or browser for remote viewing and record keeping.
• Probe health indicator — shows when the probe needs attention, alongside simple 2-point pH calibration.

Who Should Use the Bluelab OnePen

Growers who want pH, EC and temperature from a single tool, whether running one hydroponic reservoir at home or checking multiple tanks in a commercial facility. It suits growers who want digital records without a fixed monitor.

About Bluelab OnePen

The OnePen is Bluelab's 3-in-1 measurement pen for nutrient solution. It ships with a sensor cleaning brush and single-use pH 7.0, pH 4.0 and KCl storage sachets, runs on 2x AAA batteries, and carries a 2-year limited warranty (6 months on the replacement probe).

Frequently Asked Questions

Why measure pH, EC and temperature together?

EC shows how much nutrient is in the solution, pH determines how available those nutrients are to roots, and temperature affects both readings and root health. Measuring all three at once gives a complete picture of the reservoir in one step. The OnePen displays pH and EC at the same time so you can adjust without switching tools.

How often does the OnePen need calibration?

The OnePen uses a simple 2-point pH calibration with pH 7.0 and pH 4.0 solutions. Regular calibration keeps readings accurate as the electrochemical pH sensor ages. A probe health indicator helps show when the sensor needs care.

What does the Edenic app add?

Over Bluetooth, the Edenic app lets you view measurements remotely through the app or a browser, share data and receive software updates. You can also adjust settings such as backlight timing and auto-off from the app. Readings still show on the pen's own display without a phone.

What happens when the probe wears out?

The pH, EC and temperature sensors are in one replaceable probe, sold separately as the Bluelab OnePen Replacement Probe. Bluelab gives an average replacement probe life of about 18 months, depending on care. Rinsing after use and storing with KCl storage solution helps it last.

Is the OnePen waterproof?

Yes. The OnePen is IP68 rated, which means it is sealed against dust and protected for immersion in water. That makes it suited to wet reservoir environments where pens are often dropped or splashed.