CPO CPO Filtration & Circulation Systems 1 — Questions and Answers
Question 1: What is the standard turnover rate required for most public swimming pools?
- 6 hours (Correct answer)
- 12 hours
- 24 hours
- 3 hours
Correct answer: 6 hours
Most public pools require a 6-hour turnover rate, meaning the entire pool volume must pass through the filtration system at least once every 6 hours.
Question 2: When should a sand filter be backwashed?
- Every 24 hours regardless of pressure
- When pressure rises 8–10 psi above the clean operating pressure (Correct answer)
- When water turns cloudy
- When pressure drops 5 psi below normal
Correct answer: When pressure rises 8–10 psi above the clean operating pressure
A sand filter should be backwashed when the pressure gauge reads 8–10 psi above the initial clean/starting pressure, indicating accumulated debris.
Question 3: What is the primary purpose of a hair and lint strainer (pump strainer basket)?
- To balance pool pH
- To measure chlorine levels
- To protect the pump impeller from debris damage (Correct answer)
- To remove algae from water
Correct answer: To protect the pump impeller from debris damage
The hair and lint strainer captures large debris before it reaches and damages the pump impeller, protecting the pump from wear and clogging.
Question 4: What filtering medium is used in a diatomaceous earth (DE) filter?
- Fine sand
- Polyester fiber
- Crushed glass
- Fossilized algae powder coated onto filter grids (Correct answer)
Correct answer: Fossilized algae powder coated onto filter grids
DE filters use diatomaceous earth — a powder made from fossilized microscopic algae — coated on filter grids to achieve very fine particle filtration.
Question 5: What causes 'channeling' in a sand filter?
- Excess chlorine breaking down the sand
- Water finding preferential paths through worn sand instead of flowing evenly (Correct answer)
- Backwashing too frequently
- Using the wrong grade of sand
Correct answer: Water finding preferential paths through worn sand instead of flowing evenly
Channeling occurs when water bypasses proper filtration by carving paths through degraded or compacted sand, significantly reducing filter effectiveness.
Question 6: What is the main water conservation advantage of a cartridge filter over a sand filter?
- It requires less pool makeup water
- It does not require backwashing, saving significant water during maintenance (Correct answer)
- It operates at lower flow rates
- It uses recycled water for cleaning
Correct answer: It does not require backwashing, saving significant water during maintenance
Cartridge filters are cleaned by rinsing with a hose rather than backwashing, eliminating the large volumes of water wasted during sand filter backwash cycles.
CPO CPO Filtration & Circulation Systems 1
What is the standard turnover rate required for most public swimming pools?