Aquatic Facility Operator (AFO)
Certification Practice Exam Questions
And Correct Answers (Verified Answers)
Plus Rationales 2025-2026 Q&A
1. What is the ideal pH range for a swimming pool?
| | | | | | | | |
A. 6.0–6.5
B. 7.2–7.8
C. 8.0–8.5
D. 6.8–7.0
Rationale: Maintaining a pH between 7.2 and 7.8 ensures effective chlorine
| | | | | | | | | |
| disinfection and swimmer comfort.
| | |
2. The main purpose of free chlorine in a pool is to:
| | | | | | | | | |
A. Balance alkalinity
|
B. Sanitize and oxidize contaminants
| | |
,C. Reduce calcium hardness | |
D. Control pH |
Rationale: Free chlorine destroys pathogens and oxidizes organic matter,
| | | | | | | |
| keeping the water safe.
| | |
3. What is the recommended turnover rate for a public swimming pool?
| | | | | | | | | |
A. 2 hours
|
B. 8 hours
|
C. 6 hours
|
D. 12 hours|
Rationale: A six-hour turnover ensures complete circulation and adequate
| | | | | | | |
| filtration of pool water.
| | |
4. What chemical form of chlorine is most effective at killing bacteria?
| | | | | | | | | |
A. Chloramine
B. Hypochlorite ion (OCl–) | |
C. Hypochlorous acid (HOCl) | |
D. Sodium chloride |
Rationale: Hypochlorous acid is the most active and effective disinfectant
| | | | | | | | |
| form of chlorine.
| |
,5. Which factor most affects chlorine efficiency?
| | | | |
A. Calcium hardness |
B. pH level |
C. Alkalinity
D. Temperature
Rationale: As pH rises, chlorine becomes less effective because more
| | | | | | | | |
| converts to the weaker OCl– form.
| | | | |
6. What is the minimum free chlorine level for a public pool according to
| | | | | | | | | | | |
| CDC guidelines?
|
A. 0.5 ppm |
B. 1.0 ppm |
C. 2.0 ppm |
D. 3.0 ppm |
Rationale: Public pools must maintain at least 1.0 ppm free chlorine for
| | | | | | | | | | |
| effective disinfection.
|
7. Combined chlorine levels should not exceed:
| | | | |
A. 1.0 ppm |
B. 0.5 ppm |
C. 0.2 ppm |
D. 2.0 ppm |
, Rationale: Combined chlorine (chloramines) above 0.2 ppm causes odor
| | | | | | | |
| and irritation, signaling poor sanitation.
| | | |
8. The main drain of a pool assists primarily in:
| | | | | | | |
A. Heating water |
B. Adding chemicals |
C. Water circulation and debris removal
| | | |
D. Backwashing filters |
Rationale: The main drain promotes complete circulation by drawing
| | | | | | | |
| water from the pool bottom.
| | | |
9. Total alkalinity acts as a buffer to control:
| | | | | | |
A. Hardness
B. Chlorine strength |
C. pH changes
|
D. Total dissolved solids
| |
Rationale: Alkalinity stabilizes pH by resisting sudden shifts from acidic or
| | | | | | | | | |
| basic inputs.
|
10. The ideal total alkalinity for a plaster pool is:
| | | | | | | |
A. 50–80 ppm |
B. 80–120 ppm |
Certification Practice Exam Questions
And Correct Answers (Verified Answers)
Plus Rationales 2025-2026 Q&A
1. What is the ideal pH range for a swimming pool?
| | | | | | | | |
A. 6.0–6.5
B. 7.2–7.8
C. 8.0–8.5
D. 6.8–7.0
Rationale: Maintaining a pH between 7.2 and 7.8 ensures effective chlorine
| | | | | | | | | |
| disinfection and swimmer comfort.
| | |
2. The main purpose of free chlorine in a pool is to:
| | | | | | | | | |
A. Balance alkalinity
|
B. Sanitize and oxidize contaminants
| | |
,C. Reduce calcium hardness | |
D. Control pH |
Rationale: Free chlorine destroys pathogens and oxidizes organic matter,
| | | | | | | |
| keeping the water safe.
| | |
3. What is the recommended turnover rate for a public swimming pool?
| | | | | | | | | |
A. 2 hours
|
B. 8 hours
|
C. 6 hours
|
D. 12 hours|
Rationale: A six-hour turnover ensures complete circulation and adequate
| | | | | | | |
| filtration of pool water.
| | |
4. What chemical form of chlorine is most effective at killing bacteria?
| | | | | | | | | |
A. Chloramine
B. Hypochlorite ion (OCl–) | |
C. Hypochlorous acid (HOCl) | |
D. Sodium chloride |
Rationale: Hypochlorous acid is the most active and effective disinfectant
| | | | | | | | |
| form of chlorine.
| |
,5. Which factor most affects chlorine efficiency?
| | | | |
A. Calcium hardness |
B. pH level |
C. Alkalinity
D. Temperature
Rationale: As pH rises, chlorine becomes less effective because more
| | | | | | | | |
| converts to the weaker OCl– form.
| | | | |
6. What is the minimum free chlorine level for a public pool according to
| | | | | | | | | | | |
| CDC guidelines?
|
A. 0.5 ppm |
B. 1.0 ppm |
C. 2.0 ppm |
D. 3.0 ppm |
Rationale: Public pools must maintain at least 1.0 ppm free chlorine for
| | | | | | | | | | |
| effective disinfection.
|
7. Combined chlorine levels should not exceed:
| | | | |
A. 1.0 ppm |
B. 0.5 ppm |
C. 0.2 ppm |
D. 2.0 ppm |
, Rationale: Combined chlorine (chloramines) above 0.2 ppm causes odor
| | | | | | | |
| and irritation, signaling poor sanitation.
| | | |
8. The main drain of a pool assists primarily in:
| | | | | | | |
A. Heating water |
B. Adding chemicals |
C. Water circulation and debris removal
| | | |
D. Backwashing filters |
Rationale: The main drain promotes complete circulation by drawing
| | | | | | | |
| water from the pool bottom.
| | | |
9. Total alkalinity acts as a buffer to control:
| | | | | | |
A. Hardness
B. Chlorine strength |
C. pH changes
|
D. Total dissolved solids
| |
Rationale: Alkalinity stabilizes pH by resisting sudden shifts from acidic or
| | | | | | | | | |
| basic inputs.
|
10. The ideal total alkalinity for a plaster pool is:
| | | | | | | |
A. 50–80 ppm |
B. 80–120 ppm |
