What the Bluelab OnePen Replaces on a Bench
Three instruments in one body, and the two that matter most read together. pH covers 0.0 to 14.0 at ±0.05, resolved to two decimal places. Conductivity runs 0 to 10 EC at ±0.1, or 0 to 100 CF. On the parts per million scales that is 0 to 5000 at 500, or 0 to 7000 at 700. Temperature reads 0 to 50°C, or 32 to 122°F, to a tenth of a degree. The shell carries an IP68 dust and water rating, which is a measured rating rather than a claim about splashes. Two AAA cells run it. Bluetooth carries readings into the Edenic app, so a check at the tank gets logged instead of remembered.
Why a pH and EC Pen Needs a Replaceable Probe
The pH probe comes out. That single fact separates this from the sealed pens beside it, because a pH probe is a consumable and always has been. The glass and the junction change chemically with use, readings drift, and cleaning does not bring them back. On a sealed pen that is the end of the meter. Here you fit a new double junction probe and carry on, with a health indicator on screen to say when that moment is near. The conductivity side works through titanium electrodes alongside it. Bluelab backs the pen for two years and a replacement probe for six months. In the box are three 18 mL sachets, pH 7.0, pH 4.0 and KCl storage solution, along with a cleaning brush and the batteries.
Key Features
- Three readings, one body: pH, conductivity and temperature, with pH and EC shown at the same time.
- pH to ±0.05: Across 0.0 to 14.0, resolved to two decimal places at 25 degrees.
- Conductivity on four scales: 0 to 10 EC, 0 to 100 CF, 0 to 5000 ppm 500 or 0 to 7000 ppm 700.
- Replaceable pH probe: A worn probe is replaced instead of the whole meter, which sealed pens cannot do.
- Probe health indicator: On screen, so the probe gets changed before the readings mislead you.
- Double junction and titanium: Double junction on the pH side, titanium electrodes on the conductivity side.
- IP68 rated: A measured dust and water rating rather than a general claim about splashes.
- Bluetooth to Edenic: Readings log to the app for records, sharing and firmware updates.
- Two year warranty: On the pen, with six months on a replacement probe.
- Ready out of the box: Three 18 mL sachets, pH 7.0, pH 4.0 and KCl storage, plus brush and batteries.
Technical Specifications
| Specification | Value |
|---|---|
| Brand | Bluelab |
| Part Number | PENONE |
| Product | OnePen 3-in-1 meter |
| Measures | pH, conductivity and temperature |
| pH Range | 0.0 to 14.0, ±0.05 at 25°C, 0.01 resolution |
| EC Range | 0 to 10 EC or mS/cm, ±0.1, 0.01 resolution |
| CF Range | 0 to 100 CF, ±1, 0.1 resolution |
| ppm 500 Range | 0 to 5000 ppm, ±50 |
| ppm 700 Range | 0 to 7000 ppm, ±70 |
| Temperature Range | 0 to 50°C / 32 to 122°F, ±1°, 0.1° resolution |
| pH Probe | Replaceable, double junction |
| Conductivity Electrodes | Titanium |
| Probe Health Indicator | Yes |
| Ingress Rating | IP68, dust and waterproof |
| Connectivity | Bluetooth to the Edenic app |
| Power | 2 x AAA alkaline batteries |
| In the Box | OnePen, 3 x 18 mL sachets (pH 7.0, pH 4.0, KCl storage), cleaning brush, 2 x AAA |
| Warranty | 2 years on the pen, 6 months on a replacement probe |