Pool Water Chemistry Flashcards

ORP (Oxidation-Reduction Potential) in pool water testing measures:

Answer: The killing power and disinfection capacity of the sanitizer

ORP measures the electrochemical potential of pool water to oxidize and destroy pathogens, reflecting overall sanitizer effectiveness.

What minimum ORP value (millivolts) is generally accepted as adequate for swimming pool disinfection?

Answer: 650 mV

An ORP of 650 mV or higher is widely accepted as indicating sufficient disinfection capacity to inactivate most pathogens.

Elevated phosphate levels in pool water are problematic primarily because phosphates:

Answer: Serve as a nutrient source that promotes algae growth

Phosphates act as fertilizer for algae; high phosphate levels fuel algae blooms even when chlorine levels appear adequate.

Superchlorination (shocking) is performed in a pool primarily to:

Answer: Destroy combined chlorine (chloramines) and oxidize organic contaminants

Shock treatment raises free chlorine to breakpoint or above, burning off chloramines, organic waste, and restoring water clarity.

Which of the following INCREASES chlorine demand in a pool?

Answer: High bather load and organic contamination

Body oils, sweat, urine, and sunscreen introduced by bathers react with and consume free chlorine, driving up demand.

According to CPO guidelines, the free chlorine level in a stabilized (CYA-present) pool should be maintained at a minimum ratio relative to cyanuric acid of approximately:

Answer: 7.5% of the CYA level

Health authorities recommend free chlorine be at least 7.5% of the cyanuric acid concentration to ensure effective inactivation of pathogens.

When adding granular pool chemicals, the recommended safe practice is to:

Answer: Pre-dissolve them in a bucket of pool water before broadcasting into the pool

Pre-dissolving granular chemicals in a bucket of pool water prevents undissolved particles from bleaching or damaging pool surfaces and liner.