Display shows LF (Low Flow) and spa will not heat properly.

Safety first: Turn off power at the GFCI breaker.

• Remove and test without filters: Take out all Marquis filter cartridges and run the spa (after restoring power) for 15–20 minutes. If LF clears and heating resumes, replace the filters.
• Inspect valves: Confirm that all slice valves are fully open. A valve left partially down after service can cause chronic low flow.
• Check for obstructions: Look into the skimmer and suction fittings for leaves, toys, or other debris. Remove any obstructions.
• Evaluate circulation pump: If LF persists with clean filters and open valves, the circulation pump may be worn. Listen for unusual noise and feel for overheating. Weak or no flow at the circulation return indicates pump replacement is likely needed.
• Inspect plumbing (advanced): If a pump replacement does not resolve LF, there may be a hidden obstruction or collapsed hose in the circulation loop, which typically requires a technician to locate and repair.