CPO Cheat Sheet 2026

The 30 highest-yield CPO facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. What is the ideal total alkalinity range for swimming pools? → 80–120 ppm
2. Water is dripping steadily from the area around the pump shaft where it enters the pump housing. This most likely indicates: → The mechanical shaft seal has failed and requires replacement
3. What is the primary purpose of superchlorination in a swimming pool? → To destroy chloramines
4. What is the primary purpose of the pump strainer basket in a pool circulation system? → To catch hair, leaves, and debris before they reach the pump impeller
5. The CPO-recommended maximum TDS increase above the pool fill water baseline is: → 1,500 ppm
6. When storing sodium hypochlorite (liquid chlorine) and muriatic acid, they must be: → Separated to prevent dangerous chemical reactions
7. What is the purpose of conducting regular safety inspections at a swimming pool? → To identify and mitigate safety hazards
8. According to NEC Article 680, what is the minimum horizontal distance that a light switch must be located from the inside walls of a swimming pool? → 5 feet
9. At what pressure rise above the clean starting pressure should a sand filter typically be backwashed? → 8–10 PSI
10. What is the maximum velocity allowed through pool suction piping? → 6 feet per second
11. What is the significance of a Langelier Saturation Index reading of exactly 0.0? → The water is in perfect calcium carbonate equilibrium
12. A pool operator notices a patron is unresponsive at the bottom of the pool. Per EAP protocols, the FIRST call to make is to: → 911 (Emergency Medical Services)
13. Which chemical container material is most appropriate for storing muriatic acid? → High-density polyethylene (HDPE)
14. Why is cyanuric acid (CYA) added to outdoor pools? → To protect chlorine from ultraviolet (UV) sunlight degradation
15. The ideal range for Calcium Hardness in a swimming pool is generally accepted to be: → 200 - 400 ppm
16. What is the maximum recommended combined chlorine level in pool water per NSPF CPO standards? → 0.2 ppm
17. What is the maximum turnover rate most health codes require for a standard public swimming pool? → Every 6 hours
18. Corrosion inside a pool heater's copper heat exchanger is most commonly caused by: → Chronically low pH (acidic water) that aggressively attacks copper surfaces
19. A 80,000-gallon pool needs superchlorination. Combined chlorine reads 0.8 ppm. Approximately how much sodium hypochlorite (12.5 percent) is needed? → 4.3 gallons
20. What is the recommended pH range for commercial spa or hot tub water? → 7.2–7.8
21. What ORP (Oxidation-Reduction Potential) reading generally indicates adequate sanitizing capacity in spa water? → 650–750 mV or higher
22. Per ANSI Z358.1, emergency eyewash stations near chemical storage areas must provide continuous flushing for a minimum of: → 15 minutes of tepid water flow
23. What is the purpose of a pool operating permit issued by a health authority? → To authorize operation of a public pool after passing a health inspection
24. Sodium bicarbonate is used in pool water management to: → Raise total alkalinity with minimal impact on pH
25. What is the recommended pH range for swimming pool water according to CPO standards? → 7.2–7.8
26. What is the minimum wire gauge required for pool bonding conductors under NEC Article 680? → 8 AWG solid copper
27. A combined chlorine reading comes back at 0.6 ppm. What does this indicate and what action is required? → Chloramines have formed; shock treatment (breakpoint chlorination) is needed
28. At a pool pH of 7.5, approximately what percentage of free chlorine exists as the active hypochlorous acid (HOCl) form? → About 50%
29. Scale deposits forming inside a pool heater's heat exchanger are most commonly caused by: → High calcium hardness combined with elevated pH and total alkalinity
30. How frequently must a CPO test pool water chemistry during operating hours? → At least every 2 hours during operating hours