Ohaus Starter ST300
A handheld from a lab-equipment maker, for labs standardised on Ohaus. Other buyers get the same accuracy for less.
Amazon $455.32$455.32
The Ohaus Starter ST300 is the better ph meter overall, rated 3.4 to 3.1. The Ohaus Starter ST300 leads on accuracy, features and calibration. The Bluelab Combo Meter wins on extra readings and price. The Bluelab Combo Meter costs $175.33 less ($279.99 vs $455.32).
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 Combo Meter
A grower’s meter for checking pH and nutrient strength in reservoirs. It has the longest warranty here.
Amazon $279.99$279.99
Which should you buy?
- Choose the Ohaus Starter ST300 for accuracy (±0.01 pH vs ±0.1 pH), features (replaceable probe, automatic temperature compensation, waterproof (IP54), stores readings vs replaceable probe, automatic temperature compensation) and calibration (3-point calibration vs 2-point calibration).
- Choose the Bluelab Combo Meter for extra readings (conductivity (EC/TDS) vs pH and temperature only) and price ($279.99 vs $455.32).
Scores side by side
Each factor is scored 0-100 against the same fixed reference points for every portable meters ph meter; a clear win is highlighted. How we rank explains each one.
| Factor weight | Ohaus Starter ST300 | Bluelab Combo Meter |
|---|---|---|
| Overall rating | 3.4/5 | 3.1/5 |
| Accuracy 30% | 81 ±0.01 pH | 19 ±0.1 pH |
| Calibration 15% | 85 3-point calibration | 50 2-point calibration |
| Features 20% | 82 replaceable probe, automatic temperature compensation, waterproof (IP54), stores readings | 55 replaceable probe, automatic temperature compensation |
| Extra readings 10% | 0 pH and temperature only | 70 conductivity (EC/TDS) |
| Price 15% | 12 $455.32 | 33 $279.99 |
| Warranty 10% | 0 warranty not published, scored as none | 100 5-year meter warranty |
Specifications
| Ohaus Starter ST300 | Bluelab Combo Meter | |
|---|---|---|
| pH measurement | ||
| Accuracy | ±0.01 pH | ±0.1 pH |
| Resolution | 0.01 pH | 0.1 pH |
| Range | 0 to 14 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 | IP54 | - |
| Stored readings | 30 readings | - |
| Battery life | 500 hours | - |
| Weight | 160 g | - |
| Meter warranty | - | 5 years |
| Probe warranty | - | 6 months |