Bluelab pH Pen by Bluelab — Waterproof pH & Temperature Meter for Hydroponics
BLL-METER-PH-PEN
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Pairs well with
The Bluelab pH Pen is a waterproof, pocket-sized pH and temperature meter built for growers who check their reservoir every single day. It reads pH across the full 0.0–14.0 range to ±0.1 accuracy with automatic temperature compensation, calibrates to two reference points for maximum precision, and floats if you drop it in the res. One AAA battery, one year warranty, made in New Zealand by one of the most trusted names in hydroponics measurement.
Specifications
- Calibrate at least once a week — pH probes drift over time and a poorly calibrated pen is worse than no pen at all. Use pH 7.0 buffer first, then pH 4.0 for a full two-point calibration.
- Always rinse the probe with clean water before dipping into a new solution. Cross-contaminating your nutrient solution with calibration buffer will throw off readings.
- Store the probe in Bluelab Probe Care KCI storage solution when not in use — keeping the probe hydrated extends its lifespan significantly.
- Check pH daily during peak feeding cycles, particularly in DWC and NFT systems where pH can shift fast between feeds.
How to Use
Pairs Well With
Check EC alongside pH for complete control over nutrient strength and uptake at every feed.
Hydroponic NutrientsEvery nutrient mix needs a pH check before it hits your plants. Keep the pen close.
All Environmental MonitorsBrowse the full range of Bluelab and other measurement tools for complete grow room monitoring.
FAQ
How often should I calibrate the Bluelab pH Pen?
Calibrate at least once a week under normal use. If you're checking solution multiple times daily, or if readings start looking inconsistent, calibrate more frequently. A drifted probe gives you false confidence — if you're not calibrating regularly, you may as well be guessing.
What calibration solutions do I need?
You need pH 7.0 buffer solution and pH 4.0 buffer solution for a full two-point calibration. Always calibrate to pH 7.0 first, then pH 4.0. Bluelab calibration solutions are specifically formulated for Bluelab instruments and are the recommended choice.
Is the Bluelab pH Pen fully waterproof?
Yes. The Bluelab pH Pen is fully waterproof and will float if dropped in your reservoir. It's designed for use in wet hydroponic environments where brief submersion is a real possibility.
What does automatic temperature compensation mean?
pH readings are affected by water temperature — the same solution reads differently at 18°C versus 28°C. Automatic temperature compensation (ATC) means the pen detects the water temperature in real time and adjusts its pH reading accordingly. You get an accurate pH reading regardless of solution temperature without any manual correction.
What pH range should I target in hydroponics?
For most hydroponic systems and coco coir, target 5.5–6.2 pH. For soil growing, 6.0–7.0 is generally the right window. Staying within these ranges keeps macro and micronutrients available for uptake — stray too far in either direction and you start seeing deficiency symptoms even when nutrients are present in solution.
How long does the battery last?
Battery life varies with usage frequency, but the auto-off function activates after a period of inactivity to extend battery life significantly. One AAA battery typically lasts several months under regular daily use. A replacement AAA battery is available at any supermarket or hardware store.
Your Reservoir Deserves Accurate pH
Bluelab pH Pen in stock now — made in New Zealand, backed by a 1-year warranty. Free shipping on orders over $499*