CAT Aquatic Technicians Skills and Knowledge Areas 3 — Questions and Answers
Question 1: Which method is used to eliminate chloramines from a pool by adding enough chlorine to reach a specific oxidation threshold?
- Superchlorination at 1 ppm above normal
- Breakpoint chlorination (typically 10x the combined chlorine level) (Correct answer)
- Adding a non-chlorine shock oxidizer only
- Draining and refilling 50% of the pool water
Correct answer: Breakpoint chlorination (typically 10x the combined chlorine level)
Breakpoint chlorination requires adding chlorine to approximately 10 times the combined chlorine reading to fully oxidize chloramines.
Question 2: A pool heater fails to ignite. After confirming gas supply is adequate, what should the technician check next?
- Calcium hardness levels in the pool water
- Flow switch or pressure switch to ensure adequate water flow (Correct answer)
- Cyanuric acid concentration
- Backwash valve position on the filter
Correct answer: Flow switch or pressure switch to ensure adequate water flow
Pool heaters have a flow switch or pressure switch that prevents ignition if water flow is insufficient, protecting the heat exchanger.
Question 3: When reading a multiport valve position, 'RECIRCULATE' bypasses which component?
- The pump
- The heater
- The filter (Correct answer)
- The chlorinator
Correct answer: The filter
The RECIRCULATE position sends water from the pump back to the pool without passing through the filter media.
Question 4: What does a saturation index (Langelier Saturation Index) value of +0.5 indicate about pool water?
- The water is slightly corrosive
- The water is balanced
- The water is slightly scale-forming (Correct answer)
- The water is dangerously over-saturated
Correct answer: The water is slightly scale-forming
An LSI above 0 indicates scale-forming (calcium deposits) tendency; +0.5 is mildly scale-forming but outside the ideal -0.3 to +0.3 range.
Question 5: A salt chlorine generator (SWG) is producing low chlorine output even though salt levels are correct. What is the most common cause?
- pH is too low (below 7.0)
- Calcium buildup on the electrolytic cell plates (Correct answer)
- Total alkalinity is above 120 ppm
- Water temperature is above 85°F
Correct answer: Calcium buildup on the electrolytic cell plates
Calcium scale deposits on the electrolytic cell reduce its ability to generate chlorine and must be cleaned with an acid wash.
Question 6: Under OSHA guidelines, when handling concentrated muriatic acid for pool pH adjustment, a technician must wear:
- Only nitrile gloves
- Chemical splash goggles, acid-resistant gloves, and a face shield (Correct answer)
- Standard work gloves and safety glasses
- A dust mask and latex gloves
Correct answer: Chemical splash goggles, acid-resistant gloves, and a face shield
Muriatic acid (hydrochloric acid) is highly corrosive and requires full PPE including chemical splash goggles, acid-resistant gloves, and a face shield.
Question 7: What is the primary purpose of a pool skimmer weir door?
- To prevent debris from re-entering the pool after being skimmed
- To regulate the flow of water into the skimmer and maintain a consistent surface skimming action (Correct answer)
- To protect the pump from large debris entering the suction line
- To equalize pressure between the skimmer and main drain
Correct answer: To regulate the flow of water into the skimmer and maintain a consistent surface skimming action
The weir door floats to create a surface-skimming action, pulling the top layer of water (where oils and debris accumulate) into the skimmer.
CAT Aquatic Technicians Skills and Knowledge Areas 3
Which method is used to eliminate chloramines from a pool by adding enough chlorine to reach a specific oxidation threshold?