Pool Water Chemistry Flashcards

What is the ideal calcium hardness range for swimming pool water?

Answer: 200–400 ppm

CPO standards recommend 200–400 ppm calcium hardness to keep water balanced and prevent both corrosion and scale.

Water with LOW calcium hardness (soft water) is most likely to cause:

Answer: Corrosion and etching of plaster and metal fittings

Soft water is aggressive and will leach calcium from plaster, grout, and metal equipment to satisfy its mineral deficit.

Which chemical is used to raise calcium hardness in pool water?

Answer: Calcium chloride

Calcium chloride is the standard hardness increaser; it dissolves quickly and adds calcium ions without significantly affecting pH.

Elevated Total Dissolved Solids (TDS) in pool water can cause:

Answer: Eye and skin irritation and reduced efficiency of disinfection

High TDS interferes with water balance, causes cloudiness, eye irritation, and makes chemicals less effective at their target concentrations.

The CPO-recommended maximum TDS increase above the pool fill water baseline is:

Answer: 1,500 ppm

TDS should not exceed 1,500 ppm above the source water TDS level; beyond this, partial or full water replacement is recommended.

Iron present in pool water at elevated levels typically causes:

Answer: Green or brown staining on surfaces and water discoloration

Iron oxidizes in chlorinated water and precipitates as rust-colored (brown/red) stains on surfaces and turns water green or brown.

A sequestering (chelating) agent is added to pool water primarily to:

Answer: Bind metals in solution to prevent staining and precipitation

Sequestering agents chemically bind metal ions such as iron, copper, and manganese, keeping them in solution and preventing stain formation.