Spa makes loud banging or knocking noises when pumps start or stop.

Safety first: Turn off power at the GFCI breaker before entering the equipment bay.

• 1. Bleed air: Remove air from pump and plumbing by loosening unions and running pumps briefly after retightening.
• 2. Inspect plumbing supports: Check that PVC pipes are properly supported and not free to move excessively. Add clamps or supports where needed.
• 3. Check pump mounts: Ensure pumps are securely bolted to the base and that rubber isolation pads are intact.
• 4. Inspect check valves: If noise coincides with pump shutoff, a check valve may be slamming. Replace with a soft-seat or spring check valve compatible with PDC Spas plumbing.