Milwaukee pH55 Pro
#11 in Pen testersFull review
A low-cost pen with a replaceable electrode, for pools, gardens and aquariums. The Apera PH60 is more accurate for a little more.
Amazon $77.90$77.90
The Milwaukee pH55 Pro is the better ph meter overall, rated 3.0 to 2.7. The Milwaukee pH55 Pro leads on features and warranty. The Milwaukee pH55 Pro costs $12.05 less ($77.90 vs $89.95).
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 pH Pen
#13 in Pen testersFull review
A simple, tough pen for growers checking nutrient pH. The PenPlus costs a little more and adds a replaceable probe.
Amazon $89.95$89.95
Which should you buy?
- Choose the Milwaukee pH55 Pro for features (replaceable probe, automatic temperature compensation, waterproof (IP65) vs automatic temperature compensation, waterproof) and warranty (2-year meter warranty vs 1-year meter warranty).
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 | Milwaukee pH55 Pro | Bluelab pH Pen |
|---|---|---|
| Overall rating | 3.0/5 | 2.7/5 |
| Accuracy 30% | 19 ±0.1 pH | 19 ±0.1 pH |
| Calibration 15% | 50 2-point calibration | 50 2-point calibration |
| Features 20% | 70 replaceable probe, automatic temperature compensation, waterproof (IP65) | 40 automatic temperature compensation, waterproof |
| Extra readings 10% | 0 pH and temperature only | 0 pH and temperature only |
| Price 15% | 89 $77.90 | 82 $89.95 |
| Warranty 10% | 25 2-year meter warranty | 0 1-year meter warranty |
Specifications
| Milwaukee pH55 Pro | Bluelab pH Pen | |
|---|---|---|
| pH measurement | ||
| Accuracy | ±0.1 pH | ±0.1 pH |
| Resolution | 0.1 pH | 0.1 pH |
| Range | -2 to 16 pH | 0 to 14 pH |
| Calibration | 2-point | 2-point |
| Temperature compensation | Yes | Yes |
| Other readings | ||
| Conductivity (EC/TDS) | No | No |
| ORP | No | No |
| Salinity | No | No |
| Build | ||
| Replaceable probe | Yes | No |
| Waterproof rating | IP65 | Waterproof |
| Battery life | 300 hours | - |
| Weight | 99 g | - |
| Meter warranty | 2 years | 1 year |
| Probe warranty | 6 months | - |