Display shows FLO and heater will not turn on; circulation appears weak or absent.

Safety first: Turn OFF power at the breaker before removing filters or opening any unions.

• Clean filters:
  • Remove all filter cartridges and rinse thoroughly.
  • Temporarily run the spa without filters to see if FLO clears (do not leave filters out long-term).
• Bleed air from system:
  • Loosen the union on the circulation pump until water seeps out, then retighten.
  • Do the same on the heater unions if accessible.
• Check water level and valves:
  • Ensure water level is adequate and all slice valves are fully open.
• Inspect flow switch:
  • Locate the flow switch in the plumbing near the heater (often a tee with two wires).
  • Check for kinks or blockages around it.
  • With power OFF, disconnect and reconnect the flow switch wires to ensure a good connection.
• Replace flow switch if necessary:
  • If good flow is present but FLO persists, the flow switch may be stuck or failed.
  • Replace with a USSPA-compatible flow switch, ensuring correct orientation (arrow in direction of flow).