I have an electronic water filler. The water supply from the solenoid is connected to the return pipe(after the pump), the inexperience PB installed a regular solenoid, not the anti-siphon type. I plan to replace it with an anti-siphon type, for extra protection against back flow from the pool water, I plan to install an inline check valve, should I install it after or before the solenoid? How about one after and one before? It never hurts to install extra check valves, right?