NASCO Facility Operations & Maintenance 4 — Questions and Answers
Question 1: A pool operator smells a strong chlorine odor near an indoor pool with high bather load. The most likely explanation is:
- Too much free chlorine in the water
- Elevated chloramine formation from swimmer waste (Correct answer)
- A faulty UV system adding excess ozone
- High calcium hardness reacting with chlorine
Correct answer: Elevated chloramine formation from swimmer waste
A strong 'chlorine smell' almost always indicates chloramines (combined chlorine) reacting with nitrogen from urine, sweat, and other organic matter — not excess free chlorine.
Question 2: What is breakpoint chlorination?
- The point at which the filter must be backwashed
- Adding enough chlorine to destroy all combined chlorine and reach a free residual (Correct answer)
- Lowering pH below 7.0 to activate chlorine
- The maximum safe chlorine dose for a public pool
Correct answer: Adding enough chlorine to destroy all combined chlorine and reach a free residual
Breakpoint chlorination requires adding approximately 10 times the combined chlorine level in free chlorine to oxidize all chloramines and establish a free residual.
Question 3: Which type of pool drain cover is required under the Virginia Graeme Baker Act for public pools?
- Any flat metal grate
- ANSI/APSP-16 certified anti-entrapment drain covers (Correct answer)
- Drain covers with holes larger than 1 inch
- Only dual drain systems with no covers required
Correct answer: ANSI/APSP-16 certified anti-entrapment drain covers
The Virginia Graeme Baker Pool and Spa Safety Act mandates ASME/ANSI A112.19.8-certified anti-entrapment drain covers on all public pools and spas.
Question 4: How should pool chemicals be stored at an aquatic facility?
- Together in one locked room for convenience
- Oxidizers and chlorine compounds stored separately in ventilated, dry areas (Correct answer)
- In the pool equipment room next to the heater
- Mixed and pre-diluted in labeled buckets
Correct answer: Oxidizers and chlorine compounds stored separately in ventilated, dry areas
Oxidizers and chlorine compounds can react violently if mixed; they must be stored separately in cool, dry, ventilated areas away from ignition sources.
Question 5: What does a multiport valve set to 'recirculate' do on a sand filter system?
- Bypasses the filter and sends water directly through the pump and back to the pool (Correct answer)
- Backwashes the filter with fresh water
- Closes all flow completely
- Sends water to a waste line
Correct answer: Bypasses the filter and sends water directly through the pump and back to the pool
The recirculate setting bypasses the filter media, circulating pool water through the pump without filtration — used when adding chemicals for mixing.
Question 6: What is the recommended total alkalinity range for swimming pool water?
- 20–50 ppm
- 80–120 ppm (Correct answer)
- 150–200 ppm
- 250–300 ppm
Correct answer: 80–120 ppm
Total alkalinity of 80–120 ppm provides a buffer that stabilizes pH and prevents rapid swings from chemical additions or environmental factors.
Question 7: An aquatic facility's pool heater is cycling on and off rapidly (short-cycling). What is the most likely cause?
- Inadequate water flow through the heater (Correct answer)
- High chlorine demand
- Incorrect pH level
- Excessive cyanuric acid
Correct answer: Inadequate water flow through the heater
Short-cycling in pool heaters is most commonly caused by insufficient water flow, which triggers the flow switch to shut down the heater before the set temperature is reached.
NASCO Facility Operations & Maintenance 4
A pool operator smells a strong chlorine odor near an indoor pool with high bather load.
The most likely explanation is: