Shock treatment may be recommended in the following cases: water filling, particularly dirty water (after a cyclone), green or cloudy pool, after an ear infection or collective angina of the children who frequent it, in case of doubt about its sanitary quality, as a preventive measure, once a year. Shock treatment is also recommended in the spring, when your pool is restarted. After a period of wintering, the water must be thoroughly cleaned before the first swim. If there is an imbalance and the chlorine is insufficient, you can also do a shock treatment.