Every day would be ideal but it’s a bit much for most people. Commercial pools are required to check chlorine levels every hour and record their findings in a log, however, the home pool owner should check their pH and chlorine levels 2-3x per week. If the pH level has changed, check the TA level. Total Alkalinity levels tend to fluctuate less, so weekly testing is fine. Calcium Hardness and Cyanuric acid levels change slowly, so monthly testing is recommended.