OnePen by Bluelab — pH, EC & Temperature in One Meter
BL-MTR-PEN-ONE
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Pairs well with
The Bluelab OnePen measures pH, conductivity (EC) and temperature from a single probe — one dip covers the whole reservoir check. It reads to two decimal places with ±0.05 pH accuracy, shows two parameters on screen at once, syncs to the Edenic app over Bluetooth, and when the probe eventually wears out you replace the probe, not the pen. IP68 waterproof and built for real grow rooms.
Specifications
- Before first calibration, hydrate the pH glass bulb for 24 hours: a few drops of KCl storage solution on the sponge inside the storage cap, cap fitted. A dehydrated bulb drifts, reads stuck near pH 7 and can break.
- Do not soak the titanium EC electrodes in KCl for any length of time — Bluelab warns against it. The cap-sponge method hydrates the bulb without bathing the electrodes.
- Never use RO, distilled or deionised water on the probe, and clean with Bluelab pH Probe Cleaner only — Bluelab's Conductivity Probe Cleaner is not compatible with the OnePen.
- The calibration check mark flashes after 30 days as your recalibration reminder — keep fresh pH 7.0 and 4.0 sachets on hand.
How to Use — First Use Setup
Pairs Well With
Keep a spare on the shelf — probes average around 18 months of life, and a swap restores full accuracy in minutes.
Calibration & pH ControlpH 7.0 and 4.0 sachets, KCl storage solution and pH adjusters — everything the OnePen needs to stay accurate.
Bluelab Wi-Fi GuardianComplement manual pen checks with 24/7 continuous monitoring and remote alerts on the same parameters.
FAQ
Does the OnePen measure pH and EC at the same time?
Yes. The dual display shows two parameters at once — cycle between pH/Temp, EC/Temp and EC/pH modes with the CAL button, all from a single probe dip.
Is the Bluelab OnePen waterproof?
Yes. It carries an IP68 dustproof and waterproof rating, built for wet grow rooms and reservoir work.
Do I need to soak the probe before first use?
Yes. Bluelab recommends hydrating the pH glass bulb for 24 hours before initial calibration — a few drops of KCl storage solution on the sponge inside the storage cap. Don't soak the titanium EC electrodes in KCl, and never use RO, distilled or deionised water.
How often should I calibrate the OnePen?
The pen tracks it for you — the calibration check mark flashes 30 days after your last successful pH calibration. Always calibrate pH 7.0 first, then 4.0 or 10.0; EC is factory calibrated.
Does the OnePen read in ppm as well as EC?
Yes. Conductivity can be displayed as EC, CF, ppm 500, ppm 700 or mS/cm, so it matches whichever scale your feed chart uses.
Can I replace just the probe rather than buying a new pen?
Yes. The OnePen uses the genuine Bluelab OnePen Replacement Probe — a tool-free swap that restores pH, EC and temperature accuracy. Note the pen only accepts genuine Bluelab probes; imitations are rejected with a "PROBE INVALID" error.
Does it connect to my phone?
Yes. The OnePen pairs over Bluetooth with Bluelab's free Edenic app to record, store, categorise and share measurements — handy for tracking reservoir trends across a full crop cycle.
One Pen. Three Readings. No Compromises.
The full reservoir check in one dip — shipped fast Australia-wide.