Oakton pHTestr 30
#3 in Pen testersFull review
A lab-brand pocket tester with a replaceable module, for labs and schools that already stock Oakton parts.
Amazon $136.22$136.22
The Oakton pHTestr 30 is the better ph meter overall, rated 3.7 to 3.4. The Oakton pHTestr 30 leads on accuracy, calibration and price. The Bluelab OnePen wins on extra readings and features. The Oakton pHTestr 30 costs $112.78 less ($136.22 vs $249).
Prices were last checked November 9, 2026. Product prices and availability are accurate as of that date and are subject to change; the price and availability shown on Amazon or the retailer's site at the time of purchase apply. As an Amazon Associate we earn from qualifying purchases.
Bluelab OnePen
#6 in Pen testersFull review
A connected pen for serious hydroponic growers who want pH and nutrient readings logged to their phone. Most buyers get more for less from the Apera PC60.
Amazon $249$249
Which should you buy?
- Choose the Oakton pHTestr 30 for accuracy (±0.01 pH vs ±0.05 pH), calibration (3-point calibration vs 2-point calibration) and price ($136.22 vs $249).
- Choose the Bluelab OnePen for extra readings (conductivity (EC/TDS) vs pH and temperature only) and features (replaceable probe, automatic temperature compensation, waterproof (IP68), stores readings vs replaceable probe, automatic temperature compensation, waterproof (IP67)).
Scores side by side
Each factor is scored 0-100 against the same fixed reference points for every pen testers ph meter; a clear win is highlighted. How we rank explains each one.
| Factor weight | Oakton pHTestr 30 | Bluelab OnePen |
|---|---|---|
| Overall rating | 3.7/5 | 3.4/5 |
| Accuracy 30% | 81 ±0.01 pH | 38 ±0.05 pH |
| Calibration 15% | 85 3-point calibration | 50 2-point calibration |
| Features 20% | 80 replaceable probe, automatic temperature compensation, waterproof (IP67) | 100 replaceable probe, automatic temperature compensation, waterproof (IP68), stores readings |
| Extra readings 10% | 0 pH and temperature only | 70 conductivity (EC/TDS) |
| Price 15% | 64 $136.22 | 38 $249 |
| Warranty 10% | 0 warranty not published, scored as none | 25 2-year meter warranty |
Specifications
| Oakton pHTestr 30 | Bluelab OnePen | |
|---|---|---|
| pH measurement | ||
| Accuracy | ±0.01 pH | ±0.05 pH |
| Resolution | 0.01 pH | 0.01 pH |
| Range | -1 to 15 pH | 0 to 14 pH |
| Calibration | 3-point | 2-point |
| Temperature compensation | Yes | Yes |
| Other readings | ||
| Conductivity (EC/TDS) | No | Yes |
| ORP | No | No |
| Salinity | No | No |
| Build | ||
| Replaceable probe | Yes | Yes |
| Waterproof rating | IP67 | IP68 |
| Connectivity | - | Bluetooth app |
| Battery life | 500 hours | - |
| Weight | 90 g | - |
| Meter warranty | - | 2 years |
| Probe warranty | - | 6 months |