The most common cause for pH measurement inaccuracies is an unclean or improperly cleaned electrode. This is very important to note, because during calibration, the instrument assumes that the electrode is clean and that the standardization curve created during the calibration process will remain a valid reference until the next calibration. pH meters on the market today will allow an offset voltage of approximately ±60 mV. The deviation from 0 mV is not unusual but ideally should be no greater than ±30 mV. The calibration process compensates for the change in offset voltage. If the mV offset continues to deviate and the meter is calibrated with a dirty electrode then inaccurate readings will result as any changes to the surface occurs.
The HI70774L Pool Line Cleaning Solution is ideal for Service Technicians in the routine maintenance of process pH and ORP probes used in monitoring and control of swimming pools, hot tubs, and spas. The cleaning solution will ensure that the probes are cleaned of any oils that have accumulated on the probes. The proper maintenance and calibration of pH and ORP probes is critical when using with process meters for maintaining desired set points.
Cleaning is a fast and effective routine that should be performed on a regular basis as a preventative measure against using a dirty electrode and to ensure that the junction is not clogged. By simply immersing the electrode in the HI70774L cleaning solution for 15 to 20 minutes will dissolve any oily residues. The probe should then be placed in storage solution for 15 minutes to allow for hydration of a pH or ORP electrode. After hydration then the probe can be calibrated.