CPO Operation and Maintenance 2 — Questions and Answers
Question 1: A sand filter's pressure gauge reads 10 PSI above its clean starting pressure. What does this indicate and what action is required?
- Continue normal operation; pressure fluctuations are normal
- Backwash the filter to remove accumulated debris (Correct answer)
- Replace the filter sand immediately
- Reduce pump speed to lower the pressure
Correct answer: Backwash the filter to remove accumulated debris
A pressure rise of 8–10 PSI above the initial clean pressure indicates the filter media is dirty and backwashing is required to restore proper flow.
Question 2: What is the maximum turnover rate most health codes require for a standard public swimming pool?
- Every 2 hours
- Every 4 hours
- Every 6 hours (Correct answer)
- Every 8 hours
Correct answer: Every 6 hours
Most jurisdictions require a pool's entire water volume to pass through the filtration system at least once every 6 hours.
Question 3: Which filter type provides the finest particle filtration, capable of removing particles as small as 2–5 microns?
- High-rate sand filter
- Cartridge filter
- Diatomaceous earth (DE) filter (Correct answer)
- Anthracite multi-media filter
Correct answer: Diatomaceous earth (DE) filter
Diatomaceous earth filters use fossilized diatom skeletons as the filter medium, allowing filtration down to 2–5 microns — the finest of common pool filter types.
Question 4: What is the primary purpose of the pump strainer basket in a pool circulation system?
- To regulate chemical dosing in the return line
- To catch hair, leaves, and debris before they reach the pump impeller (Correct answer)
- To monitor the flow rate through the system
- To filter fine particles from the water
Correct answer: To catch hair, leaves, and debris before they reach the pump impeller
The pump strainer basket protects the pump impeller from damage by capturing large debris on the suction side of the pump.
Question 5: During backwashing of a sand filter, in which direction does water flow through the filter bed?
- Downward at increased speed, same as normal filtration
- Upward through the filter bed to lift and agitate the sand (Correct answer)
- Sideways through bypass ports installed in the filter tank
- Outward radially from a central distribution pipe
Correct answer: Upward through the filter bed to lift and agitate the sand
Backwashing reverses the water flow upward through the sand, expanding and agitating the bed to flush trapped dirt out to the waste line.
Question 6: What type of valve is installed on the suction line of a pool pump to prevent water from draining back when the pump shuts off?
- Gate valve
- Ball valve
- Check valve (Correct answer)
- Butterfly valve
Correct answer: Check valve
A check valve permits water flow in only one direction, maintaining pump prime by preventing backflow through the suction line when the pump is off.
Question 7: What does 'static head' refer to in a pool hydraulic system?
- The pressure created by the weight of standing water at rest (Correct answer)
- The flow rate through the return pipes at maximum pump speed
- The difference in elevation between the pump and the pool surface
- The resistance added by filter media to the water flow
Correct answer: The pressure created by the weight of standing water at rest
Static head is the pressure exerted by the weight of water in a non-flowing system, measured in feet of water column.
CPO Operation and Maintenance 2
A sand filter's pressure gauge reads 10 PSI above its clean starting pressure.
What does this indicate and what action is required?