1. What is pH and why is it important?
The pH (or hydrogen potential) measures the acidity or basicity of an aqueous solution on a scale of 0 to 14. At pH = 7, water is neutral; at pH < 7, it is acidic; and at pH > 7, it is basic. French legislation stipulates a pH of between 6.9 and 8.2 for pool water, but the optimum value depends on the type of treatment used.
If treated with chlorine: Chlorine acts in the form of hypochlorous acid (π»ππΆπ), which dissociates into ions according to the reaction π»ππΆπ β π»βΊ + πΆππ-. The higher the pH, the more chlorine is transformed into πΆππ- ions, which are much less effective as disinfectants. Conversely, if the pH is too low, active chlorine can be wasted. The ideal range is around 7.5 to maximize its effectiveness.
If treated with bromine: Bromine acts as hypobromous acid (π»ππ΅π), which dissociates in a similar reaction (π»ππ΅π β π»βΊ + π΅ππ-). However, bromine remains effective over a wider pH range than chlorine. Ideally, the pH should be maintained at around 7.8 for a bromine treatment.
2. How to correct water pH?
To raise the pH: pH+ products generally contain sodium carbonate, or soda ash. When added to water, this product triggers an acid-base reaction with carbonic acid, releasing ions that raise the pH.
To lower pH: pH- products are often based on sodium hydrogen sulfate. When dissolved, they trigger a reaction involving the hydrogensulfate ion, which lowers the pH of the water.
3. What are the risks of an unbalanced pH?
An unbalanced pH can have a number of consequences:
pH too low (<6.9): corrosive water, irritation for bathers, accelerated wear and tear on equipment.
pH too high (>8.2): Ineffective disinfection, limescale deposits, cloudy water and discomfort for bathers.
4. To sum up: how to maintain an ideal pH?
For a healthy pool, test the pH regularly and adjust it according to your needs:
Chlorine treatment: ideal pH around 7.5.
Bromine treatment: ideal pH around 7.8.
A well-managed pH ensures effective disinfection and pleasant water for bathers!