CPO Pool Maintenance and Troubleshooting Questions and Answers 2 — Questions and Answers
Question 1: What is the most likely cause of persistent green pool water despite maintaining adequate free chlorine levels?
- High pH preventing chlorine effectiveness
- Copper contamination from corroded heat exchangers or copper-based algaecides (Correct answer)
- Low calcium hardness
- Excessive cyanuric acid
Correct answer: Copper contamination from corroded heat exchangers or copper-based algaecides
Persistent green water with adequate chlorine typically indicates dissolved copper, not algae. Copper can come from corroded heat exchangers or copper-based algaecides.
When free chlorine is adequate and properly distributed, algae cannot survive. Dissolved copper above 0.3 ppm gives water a green or blue-green tint. Treatment involves adding a metal sequestrant, correcting the corrosion source, and potentially draining and acid washing if staining has occurred.
Question 2: A pool operator notices the filter pressure gauge has dropped 5 psi below normal. What is the most likely cause?
- The filter needs backwashing
- There is an obstruction in the suction line or the pump is losing prime (Correct answer)
- The water temperature is too high
- Chemical levels are imbalanced
Correct answer: There is an obstruction in the suction line or the pump is losing prime
A pressure reading below normal indicates reduced flow reaching the filter, typically from a suction-side obstruction or failing pump.
Pressure decreasing below the baseline indicates less water reaching the filter. Common causes include clogged pump strainer basket, clogged skimmer baskets, air leak on the suction side, low water level, closed suction valve, or worn pump impeller.
Question 3: What causes white flaky deposits (scale) to form on pool tile and equipment?
- Low calcium hardness
- High calcium hardness combined with high pH and high total alkalinity (Correct answer)
- Excessive chlorine levels
- Low total dissolved solids
Correct answer: High calcium hardness combined with high pH and high total alkalinity
Scale formation occurs when calcium carbonate precipitates out of solution due to oversaturation, caused by high calcium hardness, high pH, and high alkalinity.
The three main factors are high calcium hardness (above 400 ppm), high pH (above 7.8), and high total alkalinity (above 120 ppm). The Langelier Saturation Index quantifies this tendency. Prevention involves maintaining balanced water chemistry with LSI between negative 0.3 and positive 0.3.
Question 4: Pool chlorine demand has suddenly increased dramatically. What should be investigated first?
- The pump motor
- Recent heavy rainfall, high bather loads, or a contamination event (Correct answer)
- The pool light fixtures
- The automatic cover motor
Correct answer: Recent heavy rainfall, high bather loads, or a contamination event
Sudden chlorine demand increases are typically caused by organic loading events like heavy rain, high bather loads, or contamination.
Investigate heavy rainfall (introduces nitrogen compounds and organic debris), unusually high bather loads, fecal or vomit incidents, animal contamination, algae beginning to bloom, chemical feeder malfunction, or water source change.
Question 5: What is the correct procedure for a fecal incident involving formed stool in a public pool?
- Simply scoop it out and continue normal operation
- Close the pool, remove the material, raise free chlorine to 2 ppm for at least 25 minutes (Correct answer)
- Drain the entire pool immediately
- Add algaecide and reopen after 1 hour
Correct answer: Close the pool, remove the material, raise free chlorine to 2 ppm for at least 25 minutes
For formed stool, close the pool, remove material, raise and maintain free chlorine at 2 ppm for at least 25 minutes at pH 7.5 or less per CDC guidelines.
For formed stool (lower Crypto risk): clear the pool, remove fecal material with a net, raise free chlorine to 2 ppm, verify pH is 7.5 or less, maintain for 25 minutes, then reopen. For diarrheal stool, the protocol requires chlorine at 20 ppm for 12.75 hours.
Question 6: What does a milky or cloudy appearance in pool water typically indicate?
- Proper chlorine levels
- Fine suspended particles from inadequate filtration or poor water chemistry (Correct answer)
- High bromine levels
- Normal water conditions after refilling
Correct answer: Fine suspended particles from inadequate filtration or poor water chemistry
Cloudy water indicates fine particles suspended in the water that the filtration system is not removing.
Common causes include inadequate filtration, poor water balance (high pH causing calcium precipitation), post-shock cloudiness from dead algae, low sanitizer allowing bacterial growth, environmental loading, and high TDS. Treatment involves correcting chemistry, running the filter continuously, and adding a clarifier.
CPO Pool Maintenance and Troubleshooting Questions and Answers 2
What is the most likely cause of persistent green pool water despite maintaining adequate free chlorine levels?