Pump will not start or stops shortly after starting and the controller/display shows FLO or FLOW error.

Safety first: Turn off power at the breaker before opening the pump or plumbing. Never run the pump dry.

• Check water level: Ensure the pool water level is at least halfway up the skimmer opening so the skimmer is not sucking air.
• Inspect skimmer and pump basket: Remove leaves and debris from skimmer baskets. Open the Zodiac pump lid, pull out the pump strainer basket, and clean thoroughly. Reinstall correctly and lubricate the lid O-ring with pool-safe silicone if needed.
• Verify valves: Make sure the suction and return valves (before and after the Zodiac pump) are fully open. Partially closed valves can trigger FLO.
• Backwash or clean filter: If you have a sand or DE filter, backwash until the sight glass runs clear. For cartridge filters, remove the cartridges and hose them off thoroughly. High filter pressure indicates restriction.
• Bleed air: Open the air relief valve on the filter (if equipped) and restart the pump to purge air from the system.
• Check flow switch/pressure sensor: On Zodiac variable-speed and control systems, inspect the flow switch or pressure sensor wiring for damage or loose connections. If the FLO error persists with good flow, the sensor may need replacement.

If flow is clearly strong and the error remains, contact a pool technician to test and replace the flow switch or pressure sensor.