Main pool pump loses prime or sucks air whenever solar is activated.

Safety: Turn off pumps before tightening or opening any fittings.

• Observe air bubbles: Look through the pump lid when solar engages. A sudden influx of air indicates a leak on the solar loop.
• Tighten unions: Check all unions and threaded fittings on the solar feed and return near the equipment pad. Tighten by hand plus a small wrench turn.
• Inspect vacuum relief valve: Ensure the valve is not stuck open under pressure. Replace if it leaks air when the system is running.
• Check above-water runs: If the return line drops into the pool above water level, ensure a check valve is installed to prevent air draw-back.