Aquatic Facility Operator (AFO)
Certification Practice Exam Questions
And Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A | Instant
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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 2026 Q&A | Instant
Download Pdf
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
