Bluelab pH Pen


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All the quality you would expect from a Bluelab product in a handy pen form. The Bluelab pH Pen is an ultra-reliable and fully waterproof handheld pH meter. It can quickly and accurately measure the pH and temperature of your nutrient solution so you can always get the very best results from your crops.

How It Works

Bluelab are renowned for producing the most accurate and reliable measuring devices. Contained within the Bluelab pH Pen is a unique probe. This probe measures both the temperature and the pH of a liquid. It is important to note, if the temperature of the solution is too high or low the accuracy of some pH readers can be negatively affected. Fortunately the Bluelab pH Pen contains an onboard computer that uses temperature information to ensure precise accuracy of the pH reading at all times. The information is shown on the LCD display and with this vital information, you can now adjust the pH levels of your water with confidence.

How To Use The Bluelab pH Pen

Use the Bluelab pH Pen is very simple. Just turn on the meter, dip the probe into you nutrient solution and wait for the reading to stabilise on the screen. You can 'hold' the reading by pressing on/off/hold button once. The unit will automatically turn off after a short while to preserve battery. You can press the 'Units' button to switch between F and C as your measurement choice of temperature. 

Before First Use - IMPORTANT

Before you can use your pen you must soak it in KCI pH Probe Refill & Storage Solution for 24 hours to hydrate the probe. A single use sachet that the meter can be stood in is provided in the box. You can also pour the liquid into a container that you can stand the meter in so that the probe is immersed for this period of time. Afterwards rinse the probe and then you will need to calibrate it. For this will you will need pH Buffer 4 and pH Buffer 7 (a single use sachet of each is provided in the box).


Pour out a little Buffer 7 into a cup (enough that the probe will be immersed in the liquid) Turn on the meter and dip the probe into the solution. Wait for the reading to stabilise between pH 6.6-7.5 then press and hold the 'Cal' button until 'CAL' is displayed on the screen, then release. The calibration sequence will now begin with '0' sequentially flashing across the screen, after '0000' stops flashing, pH7 is displayed and the sequence is complete. Now rinse the probe and repeat the same process using pH Buffer 4 (waiting for the reading to stabilise to pH 3.6-4.5 in the same way as above before press 'Cal'). Once this step is complete calibration is now finished and a small tick will be displayed on the screen to show this. This tick will disappear after 30 days and therefore serves as a good indicator of when to calibrate again.


pH probes are very sensitive and delicate instruments and must be treated with care. Never touch the probe as this will risk damaging it. You must also NEVER let the probe dry out. To ensure this, add a few drops of pH Probe Refill & Storage Solution to the probe storage cap every week and this should be sufficient to keep it in full working order. Always rinse the probe after use.

If the probe does dry out it must be soaked for 24 hours in the same way it is before first use (see above). After 24 hours rinse, then soak if ph Buffer 4 for 10 minutes, rinse again and perform calibration.

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