Operation and Maintenance 1 Flashcards
6 cards from real CPO practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Operation and Maintenance 1 flashcards as text
When backwashing a sand filter, the operator should stop the backwash cycle when:
Answer: The sight glass or waste discharge line runs clear
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.
After backwashing a diatomaceous earth (DE) filter, what is the required next step before returning the system to normal filtration?
Answer: Add fresh DE powder through the skimmer at the manufacturer's recommended dose
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.
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?
Answer: An air leak or obstruction on the suction side of the pump
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.
What is the correct procedure when changing the position of a multiport (spider) valve on a pool filter system?
Answer: Always shut the pump off completely before moving the valve handle
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.
What is the primary function of the floating weir flap located inside a pool skimmer throat?
Answer: To draw surface debris inward on a thin sheet of flow and prevent it from floating back out when the pump stops
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.
A pool operator must achieve a 6-hour turnover rate for a 90,000-gallon commercial pool. What minimum flow rate (in GPM) is required?
Answer: 250 GPM
Flow rate = Pool volume ÷ Turnover time in minutes. 90,000 gallons ÷ (6 hours × 60 min/hr) = 90,000 ÷ 360 = 250 GPM. This is the minimum rate the circulation system must deliver to meet the 6-hour code requirement.