pH is a term that is used to measure whether something is acidic (low pH) or basic (high pH). This reading is expressed in a scale in a range from 0-14. Swimming pool water should be maintained at a neutral pH of between 7.2-7.6. Maintaining the proper pH level helps maintain your pool equipment, allows the chemicals to be more effective and makes the water comfortable for swimming. A low pH reading can cause skin and eye irritation, damage the liner, damage the surface of concrete pools. and corrode your pool's equipment. A high pH reading could cause cloudy water, scale to form, and sanitizer to be less effective. Some of the common causes of pH changes are: * Chemicals - chlorine tablets or sticks lower pH. Granular chlorine raises pH. * Adding fresh water to your pool will change the pH levels. * Dust and rain will change the pH levels. * Swimmers and swimmers waste will tend to lower the pH. * Algae growth usually raises the pH level. It is very important that you have a good test kit for testing pH and also take a sample of your pool water on a regular basis to your pool store so they can test the readings for you and tell you how to adjust the pH level.