CPO Water Testing and Analysis 3

Question 1

How is the combined chlorine (chloramine) level calculated from pool water test results?

Accepted Answer

Total chlorine minus free chlorine

Answer

Combined chlorine equals total chlorine minus free chlorine; it represents chlorine that has reacted with nitrogen compounds and lost its disinfecting power.

Question 2

What is the primary function of cyanuric acid (CYA) when added to outdoor swimming pool water?

Accepted Answer

Protects free chlorine from degradation by UV sunlight

Answer

Cyanuric acid bonds with hypochlorous acid and shields it from UV radiation, significantly extending the effective lifespan of chlorine in outdoor pools.

Question 3

ORP (Oxidation-Reduction Potential), used to assess pool water disinfection efficacy, is measured in which unit?

Accepted Answer

Millivolts (mV)

Answer

ORP is an electrochemical measurement expressed in millivolts that indicates the overall oxidizing power and disinfection capacity of the water.

Question 4

An ORP reading of 650–750 mV in a properly maintained pool typically indicates which condition?

Accepted Answer

Adequate disinfection with effective pathogen control

Answer

Most health authorities consider an ORP of 650–750 mV the range that provides effective pathogen inactivation in pool water.

Question 5

When the combined chlorine (chloramine) level exceeds 0.2 ppm, what is the recommended corrective action?

Accepted Answer

Perform breakpoint chlorination (superchlorination)

Answer

Breakpoint chlorination involves adding enough chlorine to oxidize and destroy chloramines, restoring effective free chlorine levels.

CPO (Certified Pool Operator Exam) Practice Test

CPO (Certified Pool Operator Exam) Practice Test

CPO Water Testing and Analysis 3