Display shows HL or HLt and spa shuts down or limits operation

Safety first: Turn off power at the GFCI breaker before removing panels or filters.

Steps to clear HL:

• Cool the spa: Open the cover and allow the water to cool if it is hot to the touch.
• Clean or replace filters: Remove the filters and rinse thoroughly from inside out with a garden hose. If they are heavily stained, collapsed, or older than 1–2 years, replace with Strong Spas-compatible cartridges.
• Check for air locks: Loosen the union on the circulation pump and primary jet pump until water seeps out, then retighten. This purges trapped air that can cause localized overheating at the heater.
• Inspect pump operation: Restore power and watch the circulation pump. It should run smoothly and quietly with a strong return flow at the heater outlet. Weak or intermittent flow indicates a failing pump or blocked line.
• Verify valves: Ensure all slice valves on either side of the pump and heater are fully open and that no service valves are left partially closed.

When to call a technician: If HL returns quickly after these steps, the circulation pump may need replacement or there may be a restriction in the plumbing that requires professional diagnosis.