Test your pool/spa water to establish what the existing chemical level is in your water. To maintain the chlorine level in private pools at a rate of between 2 to 3mg/litre (ppm), add 84g per 45.5m3 per day (3oz per 10,000 gallons). For spas add at a rate of 4.2gm/2.27m3 (500gls). Maintain a level of 3mg/l (ppm). Pre-dissolve the granules and add to the pool/spa choosing a period when the pool is not in use, ideally the evening is considered the best time. Re-adjust the pH to between 7.2-7.6 for optimal bather comfort.
Never mix pool chemicals together and always test the water with a reliable tester before use.