After adding liquid chlorine to raise the free chlorine level to a safe measure, how long must patrons wait before entering the pool?

The appropriate waiting period after adding liquid chlorine, which raises the free chlorine level in the pool, is indeed 30 minutes. This time allows the chlorine to effectively mix with the pool water and lower the chlorine levels to safe concentrations for swimming.

When chlorine is added to the pool, it increases the free chlorine level temporarily, which can cause skin and eye irritation for swimmers if they enter the water too soon. The 30-minute waiting period ensures that the chlorine can dissipate adequately and that the water chemistry stabilizes, providing a safe environment for patrons.

While it may seem convenient to allow immediate entry or a shorter waiting period, safety protocols are in place to protect swimmers from potential adverse effects of elevated chlorine levels. This practice emphasizes the importance of maintaining proper pool chemistry for healthy and enjoyable swimming experiences.