Welcome to the pH and ORP Measurement Frequently Asked Questions Page. On this page you can find answers for many general questions.


pH & ORP Measurement FAQ


1. What is the maximum extension cable I can connect between the pH electrode and the meter?

2. Does pH electrode response change in time?

3. Can I install two PROBER's on one PC?

4. What is pH?

5. Does my PROBER-PH8 support two point calibration?

6. How should I store my electrode?

7. How often should I calibrate my pH meter?

1. What is the maximum extension cable I can connect between  the pH electrode and the meter?

The maximum length is typically 20 ft. Cable longer than this will act as an attenuator which will reduce the voltage meter reading, resulting in inaccurate pH or ORP measurements.

2. Does pH electrode response change in time?

Yes, the response of the pH electrode should change periodically. Your pH electrode and pH buffers should be checked systematically. Please note that better quality pH electrodes have a full range response of 96-102%.


Final advice: If the Slope response is out of range, clean the pH electrode. If cleaning does not return the pH slope’s response to an acceptable range, replace the electrode. Contaminated buffers may slightly contribute to shifted pH values. You should replace the pH buffers if the measurement is out of normal range (96-102%)

 3. Can I  install two PROBER's on one PC? 

If you have PROBER-PH8 software version 2.0 or later, the answer is absolutely. Simply connect your PROBER's to the corresponding COM ports (i.e. COM1 and COM2) on your computer. Power both PROBER's (see on pages 9-11 of the Operation Manual). Now to the easy part ("Plug and Play"). Install your software (see on page 13 of the Operation Manual) twice. While installing the second PROBER (using the setup program) when asked to choose destination location choose a different location than the one you chose for the first PROBER (default location is  C:\Program Files\EID) i.e.  you can choose for the second PROBER C:\Program Files\EID2. 


Please note: while you are logging to file you measurements, unless you give the files different names, each will be saved in the chosen directory (C:\Program Files\EID and C:\Program Files\EID2)

4. What is pH?

Webster’s Dictionary defines pH as the degree of acidity or alkalinity of a solution. More specifically, it is the logarithm of the reciprocal of the hydrogen-ion concentration in gram equivalents per liter of solution (Ex: .0000001 gram atom of hydrogen ion per liter yields a numeric reciprocal of ten million, the log of ten million equals 7, therefore 7 is the pH): a pH of 7, the value for pure distilled water, is regarded as neutral; pH values from 7 to 0 indicate increasing acidity and from 7 to 14 indicate increasing alkalinity.


As an extension of the human sensorium, the concept of pH facilitates the standardization of the individual experience. The universality of the application of these standards extends to every field of human inquiry from the science of food to the chemical industry.


No longer is there total reliance on food tasters or the vagaries of testing by trial and error. This predictability of experience readily translated into profit and potentially longer life in the case of the food taster. The concept of qualities such as fresh, sour, sweet, ripe, etc. as well as a substance’s ability to predictably perform or combine with other substances could now be measured beyond the level of the human senses.


Industry need no longer rely on word of mouth or information passed from one generation to the next for their continuance. The farmer could ascertain the qualities of the soil. The winemaker could predictably determine readiness from the grape to the bottle. The dairy farmer could replicate a pleasant experience in making cheeses. Industry and manufacturing are no less reliant on these same characteristics. Quality could now more readily be assured with the understanding of pH and its application.

5. Does my PROBER-PH8 support two point calibration?

Yes, If you have PROBER software version 2.1 or later you can easily calibrate up to 8 electrodes simultaneously. 

6. How should I store my electrode?  
The ideal solution for electrode storage is 4M KCI. pH 4 buffer, pH 7 buffer. Tap water is also acceptable. Never store your electrode in distilled water as it will destroy the glass bulb. When ordering electrode ask for EID's pH soaking bottle. It will include the correct solution for a long lasting electrode.
7. How often should I calibrate my pH meter/logger?
You should calibrate your meter prior to each use or before sequential measurements.