Measuring the pH value of the nutrient solution or the growing medium is essential, especially for hydroponic cultivation. But even when growing on soil, optimal results can only be achieved with a pH value of the water that is ideal for the plant. This can be determined easily and quickly with an electronic pH meter. Therefore, we would like to briefly introduce you to the correct use of a pH meter. You can find out more about the pH value in our report about the optimal pH value.
Determine pH value
Measuring the pH value of a liquid with an electronic pH meter is very easy. The device is switched on and the measuring probe is held in the liquid. After a short time, the value can be read on the display.
Before measuring the pH value of a nutrient solution, all fertiliser components must be added and the nutrient solution must be stirred well. If the pH value is not optimal after the measurement, it can be lowered with pH- (lye) or increased with pH+ (acid).
Care should be taken when handling the products, acids and alkalis can cause severe burns!
Calibrate
Calibration of the pH meter is essential for accurate measurement. If a pH meter is not calibrated before the first measurement and regularly thereafter, it will become increasingly inaccurate over time and will no longer show correct values.
A pH meter should be calibrated:
- before the first measurement
- subsequently every fortnight
- After cleaning
- when the probes are dried out
- when the results become inaccurate
To calibrate a pH device, one or two different calibration liquids are needed. For this purpose, it is best to read the instructions of the respective device manufacturer to find out which liquid(s) (pH value) you need or to use the manufacturer's calibration solution.
The calibration liquid should not be kept until the next measurement, otherwise it will no longer function correctly. Therefore, always fill only as much liquid into a small container as is needed and do not pour it back into the bottle!
Most instruments are calibrated with a small screwdriver via one or 2 small screws. To do this, hold the measuring probe in the calibration liquid and carefully turn the screw until the value of the calibration liquid appears in the display. The same procedure is repeated with a liquid with a different pH value. For instruments that are digitally calibrated, the procedure is described in detail in the instruction manual. In most cases, the calibration mode must be selected and the probe immersed in the appropriate liquid until the display stops flashing.
How do you clean a pH meter?
The electrodes must be cleaned regularly in order to perform accurate measurements. Salt encrustations, grease from the fingers or even dust will falsify the measurement results and make them inaccurate. Therefore, the device should be cleaned after each measurement and preferably stored in demineralised (distilled) water between measurements. Most measuring devices have a waterproof cap into which distilled water can be filled. For regular cleaning, there are also special Cleaning fluids are available for regular cleaning.
Here are some pH meters:
ADWA AD100
Low-cost, digital pH meter with automatic temperature compensation and 2-point calibration. ADWA AD 100 is not waterproof and cannot be submerged.
Hanna pHep
The handy Hanna pH meter has a pH electrode with a renewable fabric diaphragm, which extends its service life. Temperature compensation is done manually by means of an integrated temperature sensor.
Hanna Combo Meter
The Hanna Combo-Meter measures the EC value, the pH value and the water temperature. This gives you a simple and effective control of all parameters of the nutrient solution.
Bluelab Guardian Monitor
The Guardian Monitor from Bluelab reliably monitors EC value, pH value and temperature of the nutrient solution via two probes that simply hang in the water. One pH probe and one for the EC value and temperature. All three parameters can be read at a glance on the large screen. For professionals, an excellent and reliable solution.