Certification Practice Exam Questions

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

• 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:

• Balance alkalinity
• Sanitize and oxidize contaminants 1 / 4

• Reduce calcium hardness
• Control pH

Rationale: Free chlorine destroys pathogens and oxidizes organic matter,

keeping the water safe.

• What is the recommended turnover rate for a public swimming pool?
• 2 hours
• 8 hours
• 6 hours
• 12 hours

Rationale: A six-hour turnover ensures complete circulation and adequate

filtration of pool water.

• What chemical form of chlorine is most effective at killing bacteria?
• Chloramine
• Hypochlorite ion (OCl–)
• Hypochlorous acid (HOCl)
• Sodium chloride

Rationale: Hypochlorous acid is the most active and effective disinfectant

form of chlorine.

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• Which factor most affects chlorine efficiency?
• Calcium hardness
• pH level
• Alkalinity
• Temperature

Rationale: As pH rises, chlorine becomes less effective because more

converts to the weaker OCl– form.

• What is the minimum free chlorine level for a public pool according to

CDC guidelines?

• 0.5 ppm
• 1.0 ppm
• 2.0 ppm
• 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:

• 1.0 ppm
• 0.5 ppm
• 0.2 ppm
• 2.0 ppm 3 / 4

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:

• Heating water
• Adding chemicals
• Water circulation and debris removal
• 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:

• Hardness
• Chlorine strength
• pH changes
• 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:

• 50–80 ppm
• 80–120 ppm
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