Bluelab PH Probe for the Guardian and the Combo
Using either the Bluelab Combo or Guardian meter will help to give you quick and easy readings for your pH and EC levels and also comes with the option of replacing the pH probe. pH probes are made from a material that over time and use will degrade and the accuracy of your readings will diminish.
Changing your pH probe once every 6-12 months will ensure accurate readings every time. Regular calibrating and checking the meter with a buffer solution once a week will give you peace of mind that your unit is still within an acceptable range and will also let you know when your probe needs to be changed.
Why change your pH meter every time you need a new probe when you can simply change the one part that is faulty.