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
The Bluelab OnePen is the better ph meter overall, rated 3.4 to 3.1. The Bluelab OnePen leads on extra readings, features and warranty. The Hanna pHep 5 HI98128 wins on calibration and price. The Hanna pHep 5 HI98128 costs $69.01 less ($179.99 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.
Hanna pHep 5 HI98128
#10 in Pen testersFull review
A well-made pocket tester from a lab brand, for anyone who already uses Hanna buffers and electrodes. The Apera PH60 does more for less.
Amazon $179.99$179.99
Which should you buy?
- Choose the Bluelab OnePen for extra readings (conductivity (EC/TDS) vs pH and temperature only), features (replaceable probe, automatic temperature compensation, waterproof (IP68), stores readings vs replaceable probe, automatic temperature compensation, waterproof) and warranty (2-year meter warranty vs 1-year meter warranty).
- Choose the Hanna pHep 5 HI98128 for calibration (3-point calibration vs 2-point calibration) and price ($179.99 vs $249).
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 | Bluelab OnePen | Hanna pHep 5 HI98128 |
|---|---|---|
| Overall rating | 3.4/5 | 3.1/5 |
| Accuracy 30% | 38 ±0.05 pH | 38 ±0.05 pH |
| Calibration 15% | 50 2-point calibration | 85 3-point calibration |
| Features 20% | 100 replaceable probe, automatic temperature compensation, waterproof (IP68), stores readings | 70 replaceable probe, automatic temperature compensation, waterproof |
| Extra readings 10% | 70 conductivity (EC/TDS) | 0 pH and temperature only |
| Price 15% | 38 $249 | 52 $179.99 |
| Warranty 10% | 25 2-year meter warranty | 0 1-year meter warranty |
Specifications
| Bluelab OnePen | Hanna pHep 5 HI98128 | |
|---|---|---|
| pH measurement | ||
| Accuracy | ±0.05 pH | ±0.05 pH |
| Resolution | 0.01 pH | 0.01 pH |
| Range | 0 to 14 pH | -2 to 16 pH |
| Calibration | 2-point | 3-point |
| Temperature compensation | Yes | Yes |
| Other readings | ||
| Conductivity (EC/TDS) | Yes | No |
| ORP | No | No |
| Salinity | No | No |
| Build | ||
| Replaceable probe | Yes | Yes |
| Waterproof rating | IP68 | Waterproof |
| Connectivity | Bluetooth app | - |
| Battery life | - | 300 hours |
| Weight | - | 100 g |
| Meter warranty | 2 years | 1 year |
| Probe warranty | 6 months | - |