What should a pool operator do if there are complaints of red eyes in swimmers and chlorine odors are present?

When swimmers complain about red eyes and there is a noticeable chlorine odor, it typically indicates high levels of chloramines in the water. Chloramines are formed when chlorine reacts with organic matter such as sweat, urine, or skin cells. They can cause irritation to the eyes and respiratory system.

Shock treating the pool with chlorine effectively raises the chlorine level temporarily to a point that kills off the organic matter causing the chloramines. This process breaks down the combined chlorine (chloramines) and helps restore the water to a more pleasant condition for swimmers. By eliminating the chloramines, the irritation caused to swimmers' eyes and the strong chlorine smell can be mitigated.

In contrast, other options like adding calcium chloride, soda ash, or sodium bicarbonate do not directly address the underlying issue of chloramines. Calcium chloride is typically used to increase calcium hardness, which does not affect chloramine levels. Soda ash and sodium bicarbonate are used to adjust pH and total alkalinity, but they do not have a role in reducing chloramine levels in the water. Therefore, shocking the pool remains the most effective solution in this situation.