The pH measurement knowledge portal
Everything about pH electrodes
How they work, which types exist, where they are used and how to care for them - clearly explained for beginners and professionals. So your readings are right.
Where would you like to start?
Four routes through the portal - depending on whether you are just getting started or solving a specific problem.
Basics
What the pH value tells you and how an electrode measures it - no prior knowledge required.
Learn more →Electrode types
Glass electrode, combination electrode, gel or liquid electrolyte: all designs compared.
Learn more →Industries
From aquariums and pools to food production: which electrode is needed where, and why.
Learn more →Guides
Calibrating, cleaning, storing - and how to tell when it is time for a new electrode.
Learn more →Frequently asked questions
The questions we hear most often - answered briefly. Detailed step-by-step instructions are in the guides.
How often do I need to calibrate a pH electrode?
It depends on the application. For daily laboratory use, calibrate before each measurement series, or at least once a week. In an aquarium or pool, every two to four weeks is usually enough. As a rule of thumb: the more accuracy you need, the more often you should calibrate.
How do I store a pH electrode correctly?
Always moist, never dry. The ideal is a storage solution (3 mol/l KCl) in the protective cap. Distilled water is unsuitable, as it leaches ions out of the glass membrane and damages the electrode. A dried-out electrode can sometimes be revived by soaking it in KCl solution for several hours, but there is no guarantee.
How do I recognise a faulty pH electrode?
Typical signs are sluggish readings that take minutes to settle, failed calibration despite fresh buffer solutions, visible cracks in the glass membrane, or strongly fluctuating values. A slope below roughly 50 mV per pH unit also points to the end of the electrode's life.
How long does a pH electrode last?
With good care, one to three years - even unused, because the electrode ages chemically. Hot, strongly alkaline or protein-rich media shorten the lifespan considerably. Regular cleaning and moist storage extend it.
What is the difference between gel-filled and refillable electrodes?
Gel electrodes are maintenance-free and robust - ideal for beginners, aquariums and pools. Refillable liquid-electrolyte electrodes respond faster and measure more accurately, but need a little care. For demanding laboratory and industrial applications, they are usually the better choice.
Can I connect any pH electrode to any meter?
Not always. The connector type is decisive - BNC, S7 and DIN are common. Many electrodes with a BNC connector fit most meters and controllers. Before buying, check the connector on your existing device.