CPO Exam Operation and Maintenance 1

Question 1

When backwashing a sand filter, the operator should stop the backwash cycle when:

Accepted Answer

The sight glass or waste discharge line runs clear

Answer

Backwashing should continue until the water visible in the sight glass (or the waste discharge line) runs clear, indicating that trapped debris and dirty water have been fully flushed from the filter bed. Time alone is not a reliable stopping point.

Question 2

After backwashing a diatomaceous earth (DE) filter, what is the required next step before returning the system to normal filtration?

Accepted Answer

Add fresh DE powder through the skimmer at the manufacturer's recommended dose

Answer

Backwashing removes the spent DE coating from the filter grids. Fresh DE must be added through the skimmer so it coats the grids and restores filtration efficiency. Without recoating, the filter cannot remove fine particles.

Question 3

A pool pump is running but return flow is noticeably weak, and the filter pressure gauge reads lower than normal. What is the most likely cause?

Accepted Answer

An air leak or obstruction on the suction side of the pump

Answer

Low flow combined with lower-than-normal pressure points to the suction side: an air leak, blocked skimmer, or cavitation prevents the pump from priming and moving water properly. A clogged filter would show high pressure, not low pressure.

Question 4

What is the correct procedure when changing the position of a multiport (spider) valve on a pool filter system?

Accepted Answer

Always shut the pump off completely before moving the valve handle

Answer

The pump must be turned off before rotating a multiport valve handle. Turning the valve under pressure damages the internal spider gasket, which can cause internal bypassing, leaks, and costly repairs.

Question 5

What is the primary function of the floating weir flap located inside a pool skimmer throat?

Accepted Answer

To draw surface debris inward on a thin sheet of flow and prevent it from floating back out when the pump stops

Answer

The skimmer weir creates a continuous thin sheet of surface water flowing into the skimmer, which efficiently collects floating debris. When the pump shuts off, the weir falls closed, trapping debris inside the skimmer rather than letting it return to the pool.

CPO (Certified Pool Operator Exam) Practice Test

CPO (Certified Pool Operator Exam) Practice Test

CPO Exam Operation and Maintenance 1