Pool water is tested for several key parameters to ensure it is safe and properly balanced for swimmers. The main parameters tested are:

1. pH Level: Measures the acidity or alkalinity of the water. Ideal pH is between 7.4 and 7.6, which helps maintain effectiveness of disinfectants and prevents skin or eye irritation.

2. Chlorine or Bromine Levels: These are sanitizers used to disinfect the water and kill harmful bacteria. The ideal chlorine level is usually between 1.0 and 3.0 parts per million (ppm), while bromine levels are typically between 3.0 and 5.0 ppm.

3. Total Alkalinity: Measures the water’s ability to resist changes in pH. The ideal range is 80-120 ppm, which helps stabilize the pH level.

4. Calcium Hardness: Measures the concentration of calcium in the water. Too little calcium can lead to corrosion of pool equipment, while too much can cause scaling. The ideal range is typically 200-400 ppm.

5. Cyanuric Acid (Stabilizer): Helps protect chlorine from being broken down by sunlight. The ideal range is 30-50 ppm for outdoor pools.

6. TDS (Total Dissolved Solids): Measures the overall concentration of dissolved materials in the water, including minerals, salts, and contaminants. High TDS can affect water quality and the efficiency of sanitizers.

7. Copper and Iron Levels: These metals can cause staining or discoloration of the pool and its surfaces. Levels should be kept low, often below 0.3 ppm for copper and 0.1 ppm for iron.

8. Phosphates: Phosphates are nutrients that can encourage algae growth in the pool. High levels of phosphates can lead to an algae bloom even when chlorine levels are adequate. The ideal phosphate level should generally be below 100 ppb (parts per billion), with anything above 100 ppb being considered a potential risk for algae problems.