Pump is noisy with a rattling or rumbling sound that changes with flow rate.

Safety first: Turn off the pump before adjusting valves.

• Reduce speed: On variable-speed Saci pumps, lower the operating RPM and see if the noise decreases.
• Open valves fully: Ensure all suction and return valves are fully open to reduce restriction.
• Clean filters: Backwash sand filters or clean cartridges to lower system pressure.
• Check for air leaks: Inspect the pump lid O-ring and suction unions for air ingress, which can worsen cavitation.

Persistent cavitation can erode the impeller and volute; if noise continues, consult a pool professional to review pump sizing and plumbing layout.