Water Chemistry & Quality Control Flashcards

Which condition is MOST likely to cause a rapid drop in pool water pH?

Answer: Heavy rain diluting pool water

Heavy rainfall, which is slightly acidic, dilutes the pool and introduces acid that lowers pH rapidly.

Breakpoint chlorination requires adding chlorine to reach how many times the combined chlorine level?

Answer: 7.6 times

Breakpoint chlorination requires adding enough chlorine so that free chlorine reaches approximately 7.6 times the combined chlorine level to destroy chloramines.

What is the primary purpose of maintaining proper calcium hardness in pool water?

Answer: To prevent corrosion of surfaces and equipment

Proper calcium hardness (200–400 ppm) prevents corrosive water from dissolving calcium from plaster, grout, and metal fittings.

What health hazard is most directly associated with elevated combined chlorine (chloramine) levels?

Answer: Eye and respiratory irritation

Chloramines, especially nitrogen trichloride, are responsible for the characteristic 'pool smell' and cause eye, skin, and respiratory irritation.

Which factor does NOT directly affect the chlorine demand of a pool?

Answer: Pool depth

Pool depth does not directly affect chlorine demand; bather load, sunlight (UV), algae, and organic contaminants all consume chlorine.

For an indoor aquatic facility, what is the recommended maximum level for combined chlorine to ensure air quality?

Answer: 0.4 ppm

Many health codes and NASCO guidelines recommend keeping combined chlorine below 0.4 ppm at indoor pools to protect air quality.

An OTO (orthotolidine) test kit measures which water parameter?

Answer: Total chlorine only

OTO reagent reacts with all forms of chlorine (free and combined) to measure total chlorine; it cannot distinguish free from combined chlorine.