Perhaps the most well-known pool chemical, chlorine effectively sanitizes pool water by killing bacteria, algae, and other microorganisms. It comes in various forms, including liquid, granular, and tablets. Chlorine levels must be regularly monitored and adjusted to ensure optimal disinfection without causing irritation to swimmers.

The pH level of pool water determines its acidity or alkalinity. Maintaining the proper pH balance is crucial for maximizing the effectiveness of chlorine and preventing corrosion of pool equipment. pH adjusters, such as pH increasers (sodium carbonate) and pH decreasers (sodium bisulfate), are used to keep the water within the ideal pH range of 7.2 to 7.6.

Total alkalinity refers to the water's ability to resist changes in pH. Alkalinity acts as a buffer, preventing drastic fluctuations in pH levels. Sodium bicarbonate (baking soda) is commonly used to raise alkalinity levels, while muriatic acid or sodium bisulfate can be added to lower alkalinity.

Calcium hardness refers to the concentration of calcium ions in the water. Maintaining proper calcium hardness levels is essential for preventing corrosion of pool surfaces and equipment. Calcium hardness increasers, typically in the form of calcium chloride, are used to raise calcium levels when they fall below the recommended range.

Despite regular chlorine treatment, algae can still bloom in pool water, causing unsightly green or cloudy water. Algaecides are chemical formulations designed to prevent algae growth or eliminate existing algae colonies. They work alongside chlorine to keep the water clear and algae-free.

Stabilizer helps prevent chlorine degradation due to UV radiation from the sun. By stabilizing chlorine, it prolongs its effectiveness, reducing the need for frequent chlorine additions. However, excessive stabilizer levels can lead to chlorine lock, where chlorine becomes less active. Regular testing and adjustment of stabilizer levels are necessary.

Occasionally, pools may require a shock treatment to eliminate organic contaminants, such as sweat, oils, and sunscreen, that can accumulate in the water. Shock treatments involve adding a highly concentrated dose of chlorine to rapidly sanitize the pool. This process helps restore water clarity and freshness.

While pool chemicals are essential for maintaining water quality, they must be handled and stored with care. Always follow manufacturer instructions and safety precautions when handling pool chemicals. Store them in a cool, dry place away from children and pets, and never mix different chemicals together, as it can produce hazardous reactions.