pH

Also Known As: Hydrogen Ion Concentration

Pool water’s chemical balance is an important factor of its health. Testing the pool water’s pH levels is an important step in assessing the water. The measure of hydrogen ion concentration, pH is simply the balance of acidity or alkalinity of the water.

If the pH is greater than 7, it is considered alkaline. If it is below 7, it is considered acidic. That means, pH is neutral at exactly 7. However, because our eyes have a pH of 7.5, this is considered the optimal pH measurement for a swimming pool.

When the pH is too high, the water can irritate the skin and eyes. When it is too low, equipment can be damaged. In addition, chlorine becomes less effective as the pH rises. For these reasons, it is critical to monitor the pool’s pH frequently.

It’s quite difficult to maintain a particular pH at all times, so look for measurements between 7.2 and 7.8. Test kits may depend on a probe, litmus paper or with liquid or tablet reagents that change the color of the water when the pH is at certain levels.

High pH can be adjusted by adding an acid, like liquid hydrochloric acid (muriatic acid) or dry acid (sodium bisulphate). Of course, extreme care should be taken whenever handling any kinds of acids. Consult the manufacturer’s instructions for guidelines on how to safely use these products. Low pH can be adjusted by adding an alkali or base, like soda ash.

To test pH utilizing a test kit: 1. Fill the large comparator with pool water to the 44 mL mark. 2. Add 5 drops Phenol Red (R-0006). Cap and shake to mix. 3. Match the resulting color with the colors on the comparator. Record as pH. 4. If pH is too high, add R-0005, drop by drop. After each drop, count, mix, and compare with color standards until desired pH is matched. See acid demand test treatment tables to continue. 5. If pH is too low, add R-0006, drop by drop. After each drop, count, mix, and compare with color standards until desired pH is matched. See base demand test treatment table to continue.