NASCO Facility Operations & Maintenance 3 — Questions and Answers
Question 1: What does the Langelier Saturation Index (LSI) measure in pool water chemistry?
- Chlorine demand
- Water's tendency to be scale-forming or corrosive (Correct answer)
- Cyanuric acid stabilization level
- Total bacterial count
Correct answer: Water's tendency to be scale-forming or corrosive
The LSI calculates the balance of pH, alkalinity, calcium hardness, and temperature to predict whether water will deposit scale or corrode surfaces.
Question 2: A facility operator finds the pump is running but water flow to the pool is very low. What should be checked FIRST?
- Chlorinator output
- Pump strainer basket for blockage (Correct answer)
- Chemical feeder calibration
- Pool water temperature
Correct answer: Pump strainer basket for blockage
A clogged pump strainer basket is the most common cause of reduced flow and should be the first point of inspection.
Question 3: What is the minimum recommended turnover rate for a public swimming pool?
- Every 8 hours
- Every 6 hours (Correct answer)
- Every 12 hours
- Every 2 hours
Correct answer: Every 6 hours
Most public pool codes require all pool water to pass through the filtration system at least once every 6 hours to maintain water clarity and sanitation.
Question 4: Which hazard is MOST directly associated with high combined chlorine (chloramines) levels in an indoor pool?
- Algae growth
- Respiratory irritation for swimmers and staff (Correct answer)
- Scale deposits on tile
- Cloudy water only
Correct answer: Respiratory irritation for swimmers and staff
Chloramines are volatile compounds that off-gas into the air, causing eye, skin, and respiratory irritation — especially problematic in enclosed indoor facilities.
Question 5: What action should a pool operator take when total dissolved solids (TDS) exceed 1,500 ppm above the source water baseline?
- Add more chlorine
- Shock the pool with cal-hypo
- Partially drain and refill with fresh water (Correct answer)
- Increase filtration run time
Correct answer: Partially drain and refill with fresh water
Elevated TDS impairs chemical effectiveness and cannot be removed by filtration — draining and diluting with fresh water is the only remedy.
Question 6: What is the purpose of cyanuric acid (CYA) in outdoor pools?
- It raises alkalinity
- It stabilizes chlorine against UV degradation (Correct answer)
- It kills algae directly
- It lowers calcium hardness
Correct answer: It stabilizes chlorine against UV degradation
Cyanuric acid bonds with free chlorine to protect it from rapid UV sunlight degradation, extending its effective life in outdoor pools.
Question 7: Which maintenance task should be performed BEFORE reopening a pool that has been closed for the winter season?
- Immediately shocking to 10 ppm
- Inspecting and pressure-testing all plumbing and equipment (Correct answer)
- Removing all drain covers permanently
- Filling the pool with undiluted muriatic acid
Correct answer: Inspecting and pressure-testing all plumbing and equipment
A comprehensive inspection of plumbing, fittings, equipment, and drain covers must occur before reopening to identify freeze damage and safety hazards.
NASCO Facility Operations & Maintenance 3
What does the Langelier Saturation Index (LSI) measure in pool water chemistry?