Pool Maintenance and Troubleshooting Flashcards
7 cards from real CPO practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Pool Maintenance and Troubleshooting flashcards as text
Pool water appears cloudy despite free chlorine and pH being within normal range. What is the most likely cause?
Answer: Poor filtration or inadequate water circulation
When chlorine and pH are normal, cloudy water typically results from poor filtration efficiency or insufficient circulation rather than chemical imbalance.
A pool has developed a widespread green algae bloom. What is the recommended initial treatment?
Answer: Shock the pool with chlorine at approximately 10 times the normal dose
Shocking with a heavy chlorine dose is the first-line treatment to kill green algae, followed by brushing surfaces and filtering out dead algae.
Mustard (yellow) algae is particularly difficult to eliminate because it:
Answer: Is resistant to normal chlorine levels and clings tightly to pool walls
Mustard algae is chlorine-resistant at normal concentrations and adheres stubbornly to surfaces, requiring aggressive shock treatment and thorough brushing.
Black algae is the most difficult pool algae to eliminate primarily because:
Answer: It has a protective outer layer and deep roots that penetrate porous surfaces
Black algae's waxy protective coating and deep roots in plaster require aggressive physical brushing and very high chlorine concentrations to penetrate and kill.
A sand filter's clean operating pressure is 10 psi. At what pressure reading should backwashing be initiated?
Answer: 15–18 psi (5–8 psi above clean starting pressure)
Backwashing should occur when pressure rises 5–8 psi above the clean baseline, indicating sufficient dirt accumulation to reduce filtration efficiency.
After backwashing a sand filter, what step should be performed before returning to normal filtration mode?
Answer: Run on the 'rinse' setting for 30–60 seconds to re-seat the sand bed
The rinse cycle re-settles the disturbed sand bed and clears residual dirty water from the filter, preventing a turbid water surge back into the pool.
At a pool pH of 7.5, approximately what percentage of free chlorine exists as the active hypochlorous acid (HOCl) form?
Answer: About 50%
At pH 7.5, which is very close to HOCl's pKa of 7.54, the free chlorine is split roughly 50/50 between the active HOCl and the less effective hypochlorite ion (OCl-).