CPO Pool Water Chemistry 3

Question 1

Breakpoint chlorination requires adding free chlorine at approximately how many times the combined chlorine level?

Accepted Answer

7.6 times

Answer

Breakpoint chlorination requires adding roughly 7.6 times the combined chlorine level to destroy chloramines and reach breakpoint.

Question 2

Combined chlorine (chloramines) forms when free chlorine reacts with:

Accepted Answer

Nitrogen-containing compounds such as ammonia and urea

Answer

Chloramines form when free chlorine combines with ammonia and urea from sweat, urine, and body oils introduced by bathers.

Question 3

What is the maximum recommended combined chlorine level in pool water per NSPF CPO standards?

Accepted Answer

0.2 ppm

Answer

Combined chlorine should not exceed 0.2 ppm; higher levels indicate chloramine buildup causing odor and eye irritation.

Question 4

Cyanuric acid (conditioner/stabilizer) protects free chlorine from destruction by:

Accepted Answer

UV sunlight

Answer

Cyanuric acid forms a reversible bond with chlorine, shielding it from photodegradation by UV rays in sunlight.

Question 5

What is the recommended cyanuric acid range for outdoor chlorinated pools?

Accepted Answer

10–40 ppm

Answer

The CPO-recommended cyanuric acid range is 10–40 ppm; exceeding 100 ppm can over-stabilize chlorine and reduce disinfection.

CPO (Certified Pool Operator Exam) Practice Test