[sleepydoc]

There are several potential problems running the siphon to a manifold running reactors. First, the back pressure caused by the reactors will slow the flow and also not be constant, causing the siphon flow to slowly 'drift' over time. The system can accommodate this to a degree but if you're only using 1" pipes for the open channel and dry emergency you can't put a lot of flow down the open channel before it starts caveating and creating noise.

During startup, the reactors will tend to trap air, which may interfere with the development of the siphon. In addition, if the total resistance is too high, the flow will be too slow to effectively clear the air, preventing the siphon from starting at all. It may work, but you can't depend on it. Keeping it like you have it (tee'd off the return) is a better bet IMO.