Preventing backflow

[Ke]

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?

 

[JasonLion]

The important thing is to have an anti-siphon valve mounted above the maximum water level of the pool somewhere in the sequence, before, after, or part of the solenoid doesn't mater. Check valves and anti-siphon valves are not exactly the same thing, though they will have related effects. Adding the check valves won't hurt, but it is the anti-siphon valve you really need.

 

[Ke]

Thanks for the reply. The output from the solenoid is connected to the pool return pipe via a T-joint, after the pump, so there will be some kind of back pressure from the running pool water. I am worried that the anti-siphon solenoid is not "strong" enough to go against the back pressure, therefore I plan to install a check-valve after the anti-siphon solenoid.