These chlorine granules are one of the most popular products for ensuring pool and spa water is safe and bacteria free. Apply regularly to achieve the recommended free chlorine level of 3-5 mg/l (ppm) for hot tubs or 1-3 mg/l (ppm) for swimming pools. These granules are rapid dissolving, long lasting and have little effect on the pH of the water. They are suitable for shock dosing small above ground pools. You can find dosing amounts below. Key Features Granular chlorine has little effect on the pH level of the water. These stabilised chlorine granules are ideal for regular dosing of your swimming pool or spa, to produce free active chlorine which kills bacteria and other potentially harmful organisms.