Taking a reading of a solution with pH that is crucial to an experiment, manufacturing process or other projects must prize accuracy above everything (except safety, of course). For pH readings, this means making sure you note the temperature at which the pH reading was taken and making sure that the equipment is working as best as it can. That requires you, or whoever is in charge of the pH controller and other equipment, to be very detailed about the equipment's care and each reading taken.
Don't Take Cleaning for Granted
A pH sensor, pH controller and anything else that measures or moderates the pH of a solution will have electrodes that are placed in the solution to take readings. A pH controller will have additional parts in the solution that release a compound that amends the solution if the pH is out of range. All of these parts can develop residue films or even crusts that affect the values they measure. Thoroughly cleaning these parts is critical to proper operation. Even a little debris on the electrodes or other parts can skew the measurements and give you an incorrect pH reading. Don't ever assume that you can quickly clean the electrodes and they'll be fine. Give each part a good cleaning as if you were trying to get rid of the tiniest bit of debris because, technically, you are.
Always Note the Temperature During Each Reading
The temperature during a reading is another vital component of accurate measurement because the hotter a solution, the lower the pH. So, a very basic solution might still have a pH appropriate for a base, but the number won't be as high, throwing off your data. Whenever you measure the pH, always note the temperature. Many pH controllers have an automatic adjusting feature that compensates for this shift in pH, but you still want to note the actual temperature when you take readings yourself.
Choose a Set of Conditions for Calibration and Stick With Them
You'll have to calibrate pH controllers and sensors, but that temperature issue can make calibration difficult. Rather than mess with trying to convert pH numbers, just choose a set of conditions and always calibrate in those conditions. For example, if the temperature of the solution is 50 degrees Fahrenheit in the morning and 70 degrees Fahrenheit in the afternoon, calibrate only in the mornings when the temperature is at that 50-degree mark.
Equipment like pH controllers have made taking measurements and adjusting pH levels easier than before, but that doesn't mean you don't have to do any work. You need to keep the equipment very clean, avoid contamination of the solution and be sure that you are detailed about temperature levels and calibration conditions. Then your pH readings will be much more accurate. For more information, contact a company that provides things like pH controllers.