Bluelab pH Pen - Temperature Compensated Digital pH Tester
Best for: growers who want a simple, accurate handheld pH check on their nutrient solution or run-off.
Our thoughts
This is the pen most new growers should own before anything else. Getting pH right matters more than almost any other single number in growing, and this makes checking it a five-second job instead of a guessing game with strips.
The Bluelab pH Pen is a handheld device for measuring the acidity or alkalinity of your nutrient solution, with automatic temperature compensation so readings stay accurate whether your reservoir runs warm or cool. Bluelab's probes are trusted across the industry for their accuracy and reliability, and this pen also displays the temperature of your solution on screen alongside the pH reading.
How it compares
It's a focused, single-parameter alternative to combo meters and to other brands' pH testers.
- Versus the Bluelab Combo Meter or One Pen, the pH Pen is cheaper and simpler because it measures pH and temperature only, not conductivity.
- Versus a Hanna Instruments Checker or Milwaukee pH600 pocket tester, Bluelab's pens are built specifically for grow room conditions and are the most widely used brand in UK hydroponic shops for a reason.
- Versus cheap pH test strips, a digital pen gives a precise numerical reading rather than an approximate colour match, which matters when you're trying to dial in feed accuracy.
If EC isn't your immediate concern, this covers the pH side of feeding properly without paying for functions you don't need.
Usage guidance
Calibration is the single most important step in keeping a pH pen trustworthy.
Calibration
Calibrate using pH 4.0 and 7.0 buffer solution for a standard two-point calibration before first use, then periodically afterwards.
Testing
Dip the probe into your reservoir or run-off, let the reading settle, and read pH and temperature straight off the display.
Storage
Keep the probe cap topped up with storage solution between uses - letting a pH probe dry out is the most common way growers shorten its working life.
Technical specifications
- Parameter measured: pH, with temperature display
- Temperature compensation: automatic
- Calibration: 2-point, using pH 4.0 and 7.0 buffer solution
- Display: digital LCD
- Housing: waterproof, handheld pen design
- Auto-off: yes
- Typical use: hydroponic, coco and soil reservoir and run-off testing
Who this is for
- New growers who don't yet own a dedicated pH tester
- Anyone still relying on test strips and wanting a proper digital reading
- Growers who already have a separate EC pen and just need a reliable pH check
- Hydro, coco and soil growers testing feed water or run-off regularly
Particularly well suited to new growers building their first proper testing kit.
Our take
Of everything you could spend money on as a new grower, an accurate pH pen is one of the harder things to justify skipping - it's the number that decides whether your plants can actually absorb the nutrients you're feeding them.
Worth picking up if you want straightforward, reliable pH readings without paying for EC measurement you might not need yet. One we sell a lot of for new growers.
