Key chemicals for swimming pools include chlorine, used to disinfect and kill harmful bacteria; pH adjusters like sodium carbonate and muriatic acid to maintain balanced water; and algaecides to prevent algae growth. Cyanuric acid stabilizes chlorine against sunlight degradation, while calcium hardness increasers protect pool surfaces. Shock treatments are essential for breaking down contaminants. These chemicals ensure water clarity, safety, and comfort, creating a healthy swimming environment when properly balanced and maintained.