Why do I need a Top Quality Bluelab pH Meter?

Plants get their nutrients from minerals but they can only get all the right minerals they need if certain conditions are right. Think of nutrients like a lock. pH is the key. A key factor that affects food uptake is whether your solution is acid or alkaline. We measure this in pH.

The Bluelab pH Pen also measures the temperature of the solution. Temperature affects the growth rate & structure of a plant. A temperature of 18 - 22°C (65 - 72°F) is recommended.

The hand held pH pen provides a compact quick & handy way to manage the success of your crop to ensure maximum uptake of nutrients. Teamed with our Bluelab ppm or EC Pen, you have a handy, convenient & accurate system for ensuring optimum plant growth and health.

The Bluelab pH pen is not the cheapest on the market. But we've tried and been disappointed with all the cheap pH pens. Using the cheap ones for the first month or two goes well. But then we start doubting the reading, or failing to get a proper calibration, and then after a few days of guessing why the plants are responding to the water strangely, the damage is done! We've always found ourselves going back to a higher quality pH pen, such as the Bluelab pH pen.

Benefits of the Bluelab pH Pen

  • Measures pH & temperature of nutrient solution
  • Selectable temperature units °C or °F
  • Double junction probe
  • Automatic pH calibration
  • Fully Waterproof
  • Range: 0.0 - 14.0 pH, 0 - 50°C
  • Auto off
  • 1 AAA Battery Included
  • Made in New Zealand
  • 1 Year Warranty

Quick Tips

  • Please read the manual
  • Use probe storage solution in the cap (20ml is supplied in a sachet)
  • Keep the cap on when not in use
  • Calibrate regularly depending on your level of use
  • Don't continously drown it in the water reservoir
  • Don't drop it too many times - it's robust, but still can crack if knocked hard enough!
  • Following these tips will help the pH meter last for many years of use


Getting Started

Before its first use, you must hydrate & calibrate your pH pen using the guides below.

Hydrate your Bluelab pH Pen. Hydrate your pH pen in storage solution for 24 hours.

  • Make sure the pH pen is clean & free from contamination. Clean the probe using this guide.
  • Place the pH pen or probe upright in a small plastic container.
  • Add enough Storage Solution to submerge the probe tip. Alternatively, open the sachet & let the probe sit upright in the sachet.
  • Leave to soak for 24 hours.
  • After hydration, rise the probe tip in fresh water, discard the solution then follow the instructions to calibrate.

Calibrate your pH pen. Calibrate before first use & return to this guide for a monthly calibration refresher.

  • Make sure your pen or probe is clean & hydrated
  • Press “power/hold” button
  • Calibrate to pH 7
  • Place probe tip in fresh pH 7.0 Calibration Solution. Wait for reading to stabilise between pH 6.6 - pH 7.5.
  • Long press the Cal button on the pen or meter until “CAL” is displayed. Release button. A calibration sequence will start, sequentially flashing "0" across the display. After "0000" stops flashing, the sequence is complete, and “pH7” is displayed
  • Rinse
  • Rinse pen or probe tip well in clean tap water and shake off excess
  • Calibrate to pH 4
  • Place probe tip in fresh pH 4.0 (or pH 10) calibration solution. Wait for the reading to stabilise between 3.6 pH - 4.5 pH
  • Long press the Cal button until “CAL” is displayed. Release button. A calibration sequence will start, sequentially flashing "0" across the display. After "0000" stops flashing, the sequence is complete, and “pH4” (or “pH10”) is displayed
  • Confirm calibration
  • A checkmark will be displayed at the bottom of the pen or meter screen to indicate a successful calibration. It will disappear after 30 days to indicate calibration is required

When to calibrate?

  • Before first use
  • If the checkmark has disappeared from the LCD screen (30 days after first calibration)
  • If the pH measurement is different from what you expected
  • After cleaning & hydration
  • After changing the batteries

Taking your first measurement.

  • Turn the pH pen on - Press the power button. (To turn off, press & hold the power button until “OFF” is displayed.)

  • Measure pH - Remove the storage cap, place probe in solution & wait for the reading to stabilise. (To hold the reading on the display, short press the power button. To turn hold mode off, press the power button again.)

  • Measure temperature. (To switch between °C or °F hold down the Units button for 3 seconds until the temperature units start flashing.)

  • Rinse & replace storage cap solution. To ensure accurate pH readings, always rinse the probe in fresh water before replacing the cap. Add 3-5 drops of Storage Solution into the wetting seal of the cap each week. Make sure the cap is on correctly; it will click when in place.


  • Bluelab pH Pen
  • pH 4 Buffer Solution 20ml
  • pH 7 Buffer Solution 20ml
  • Storage Solution (KCl) 20ml

(SKU: 124259)

SKU 124259
Barcode # 9421024920234
Brand Bluelab
Warranty Length 1 Year
Warranty Conditions Replacement Warranty
Shipping Weight 0.30 kg
Type Test and Measurement

Replacement Warranty - Store warranty, this product needs to be returned to Aqua Gardening for testing and replacement.


Product Manual

View PDF brochure for Bluelab pH Pen

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