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 3.2. The Oakton pHTestr 30 leads on accuracy, calibration and price. The Milwaukee pH58 Max pH/ORP wins on extra readings. The Oakton pHTestr 30 costs $83.43 less ($136.22 vs $219.65).
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.
Milwaukee pH58 Max pH/ORP
#8 in Pen testersFull review
A pen for pool and water-treatment work that needs ORP as well as pH. For pH alone, cheaper pens are as accurate.
Amazon $219.65$219.65
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 $219.65).
- Choose the Milwaukee pH58 Max pH/ORP for extra readings (ORP vs pH and temperature only).
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 | Milwaukee pH58 Max pH/ORP |
|---|---|---|
| Overall rating | 3.7/5 | 3.2/5 |
| 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) | 70 replaceable probe, automatic temperature compensation, waterproof |
| Extra readings 10% | 0 pH and temperature only | 70 ORP |
| Price 15% | 64 $136.22 | 44 $219.65 |
| Warranty 10% | 0 warranty not published, scored as none | 25 2-year meter warranty |
Specifications
| Oakton pHTestr 30 | Milwaukee pH58 Max pH/ORP | |
|---|---|---|
| pH measurement | ||
| Accuracy | ±0.01 pH | ±0.05 pH |
| Resolution | 0.01 pH | 0.01 pH |
| Range | -1 to 15 pH | -2 to 16 pH |
| Calibration | 3-point | 2-point |
| Temperature compensation | Yes | Yes |
| Other readings | ||
| Conductivity (EC/TDS) | No | No |
| ORP | No | Yes |
| Salinity | No | No |
| Build | ||
| Replaceable probe | Yes | Yes |
| Waterproof rating | IP67 | Waterproof |
| Battery life | 500 hours | 250 hours |
| Weight | 90 g | 99 g |
| Meter warranty | - | 2 years |
| Probe warranty | - | 6 months |