FLO
Tuff Spas
Low Water Flow / Flow Switch Open
Display shows FLO or FL and heater will not run; sometimes pump runs continuously at low speed.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Dirty or clogged Tuff Spas filter cartridge, Air lock in circulation line, Stuck or failed flow switch, Weak or failing circulation pump
How to Fix / Troubleshooting
Safety: Turn off power at the GFCI breaker before opening unions or removing components.
- Step 1 – Check water level: Ensure water is at or slightly above the recommended fill line. Top off if low.
- Step 2 – Clean or remove filter: Remove the filter cartridge and rinse thoroughly. Try running the spa for 10–15 minutes with the filter removed to see if the FLO code clears. If it does, replace the filter.
- Step 3 – Bleed air from pump: With power off, slightly loosen the pump discharge union until air escapes and water begins to seep, then retighten. This helps clear air locks that can trigger FLO.
- Step 4 – Inspect flow switch: Locate the flow switch in the plumbing near the heater tube. Check for kinks in hoses or debris. With power off, unplug the flow switch from the control board and inspect the connector for corrosion.
- Step 5 – Test circulation pump: Restore power and observe whether the circulation pump runs smoothly. If the pump is noisy, hot to the touch, or not running, it may need replacement.
If FLO persists after filter cleaning and air bleeding, the flow switch or circulation pump is likely faulty and should be tested and replaced with the correct Tuff Spas-compatible part.
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Repair Difficulty
Medium
3/5
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