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 $129.34$129.34
The Oakton pHTestr 30 is the better ph meter overall, rated 3.7 to 3.3. The Oakton pHTestr 30 leads on accuracy. The Ohaus Starter ST20 wins on price. The Ohaus Starter ST20 costs $24.72 less ($104.62 vs $129.34).
Prices were last checked November 11, 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.
Ohaus Starter ST20
#7 in Pen testersFull review
A pen tester from a lab-balance maker, for classrooms and labs buying Ohaus gear. The Apera PH60 is more accurate for less.
Amazon $104.62$104.62
Which should you buy?
- Choose the Oakton pHTestr 30 for accuracy (±0.01 pH vs ±0.05 pH).
- Choose the Ohaus Starter ST20 for price ($104.62 vs $129.34).
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 | Ohaus Starter ST20 |
|---|---|---|
| Overall rating | 3.7/5 | 3.3/5 |
| Accuracy 30% | 81 ±0.01 pH | 38 ±0.05 pH |
| Calibration 15% | 85 3-point calibration | 85 3-point calibration |
| Features 20% | 80 replaceable probe, automatic temperature compensation, waterproof (IP67) | 80 replaceable probe, automatic temperature compensation, waterproof (IP67) |
| Extra readings 10% | 0 pH and temperature only | 0 pH and temperature only |
| Price 15% | 67 $129.34 | 76 $104.62 |
| Warranty 10% | 0 warranty not published, scored as none | 0 warranty not published, scored as none |
Specifications
| Oakton pHTestr 30 | Ohaus Starter ST20 | |
|---|---|---|
| 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 | 3-point |
| Temperature compensation | Yes | Yes |
| Other readings | ||
| Conductivity (EC/TDS) | No | No |
| ORP | No | No |
| Salinity | No | No |
| Build | ||
| Replaceable probe | Yes | Yes |
| Waterproof rating | IP67 | IP67 |
| Battery life | 500 hours | 200 hours |
| Weight | 90 g | 110 g |