The correct level of free chlorine should be maintained for several hours before and during swimming activity Chlorine levels and pH should be tested daily by use of a reliable test kit using fresh testing reagents. If pH falls below the required level add Spa Care pH and Alkalinity Increaser; if it rises above add Spa Care pH and Alkalinity Reducer. Dose pool in the evening when the pool or spa is not in use. Stabiliser levels MUST be tested fortnightly by your local pool shop or by use of a reliable test kit. Once stabiliser levels reach 50 mg/L DO NOT use this product until stabiliser levels fall below that level. INSTEAD use an unstabilised chlorine product to maintain free chlorine levels. If 50 mg/L of stabiliser is exceeded the ability of the chlorine to control algae and bacteria is reduced. UNDER NO CIRCUMSTANCES should stabiliser levels be allowed to exceed 10