Bluelab pH Pen is a hand-held device for measuring the pH (acidity or alkalinity) of your hydroponic nutrient solution. It also reads and displays the temperature of the nutrient solution on screen and it features temperature compensation, so you get highly accurate pH readings.
The Bluelab pH Pen contains a special probe which measures both the pH and temperature of a liquid. The end of the meter is dipped into the nutrient solution and switched on. After a short time, the display will settle and the pH and temperature of the liquid will be shown on the LCD readout.
The on-board computer inside the Bluelab pH Pen uses temperature information to ensure the accuracy of the pH reading by automatically compensating for any differences, meaning that you can take readings with complete peace of mind, knowing that they are proper representations of what is going on inside your nutrient solution.
The Bluelab pH Pen is water-resistant but not waterproof, so shouldn't be fully submerged for any length of time. Calibration is a simple push-button operation and the unit has an auto switch-off facility to preserve battery life.
Why should I measure pH?:
To grow plants successfully, particularly in hydroponics, it is necessary to monitor and adjust the pH of your nutrient solution on a regular basis. In general, plants grown in hydroponics like a pH of between 5.5 and 6.5 (plant species dependant) with a little bit of variation within this range. This is because plants can only absorb certain nutrients at a pH close to 5.5 and others at a pH closer to 6.5.
If your nutrient solution strays out of this optimum range for too long, your plants will not be able to absorb all the nutrients that they need and will become deficient. This leads to slowed growth and eventually sickness. To avoid pH problems, and the plant problems that it can cause, it is wise to check and adjust the pH of your nutrient solution very regularly (every day if possible).
Soil grown plants tend to like a pH of around 6.5. A good way of finding out the pH of your soil is to test the run-off water which comes out of the bottom of the pot when you water.
How to use the Bluelab pH Pen:
Before using for the first time, the Bluelab pH Pen should be soaked in KCL (potassium chloride) solution for 24 hours and then calibrated. For optimal results the meter should also be re-calibrated once a week if being used daily.
Calibration fluids (pH 4 Calibration Solution and pH 7 Calibration Solution) are available for this purpose. To calibrate your meter, remove the protective end-cap and wet the probe with clean water. Shake out the end to remove excess water and dip into calibration fluid.
Holding the calibration button will then begin the automatic calibration process. When this is complete, your Bluelab pH Pen is ready for use.
Before every use, always rinse the probe with clean water and then shake off the excess. Press the power button and dip the probe into the nutrient solution. After a few seconds the meter will beep, indicating that the pH measurement has been taken. The meter can now be removed and the display read.
The pH of your nutrient solution can then be corrected with pH Up or pH Down adjustment fluids before re-testing. The meter can be switched off by pressing the on-off button for 3 seconds. Always rinse the probe with water and shake off the excess before replacing the end-cap after use.