pH and Alkalinity?
11th June 2009

There is a lot of confusion between pH and Total Alkalinity so what is the difference?

The pH is a very important factor. Certain chemical processes can only take place when water is at a certain pH. For instance, chlorine reactions only take place when the pH has a value of between 6,5 and 8.

The pH is an indication for the acidity of a substance. It is determined by the number of free Hydrogen ions (H+) in a substance.

The result of a pH measurement is determined by a consideration between the number of H+ ions and the number of hydroxide (OH-) ions. When the number of H+ ions equals the number of OH- ions, the water is neutral. It will than have a pH of about 7.


Total Alkalinity

The Definition of Alkalinity is ; A measure of the amount of acid that a given volume of water can absorb without substantially changing its pH.

The total amount of alkaline materials present in water. Total Alkalinity is a pH buffer – the measure of the pH’s ability to change. If too high (above 200ppm), it makes pH hard to adjust. If too low (below 80ppm), the pH will fluctuate excessively.



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