My SOS is in a 45 tall. I have the return pump going through a ball valve, then an anti-siphon valve to the spray bar. The SOS end, is dropping to a ball valve then to the sump.
I put the ball valves on as precautions and to conduct maintenance. The siphon valve was a 21.00 waste of money. Drill a hole in your final bend to the spray bar right below the waterline. Once it starts sucking air...it stops pretty quickly. Or if you want to go with a siphon valve get one at Home D, or Lowes for a fraction of ordering them online...same with ball valves.
All in all, I am very pleased with the SOS. I have shut the system down, plugged the overflow main and backup drains, and everything in between and have not even come close to a flood of any sort.