Post in thread 'To trickle or not to trickle?' https://www.reef2reef.com/threads/to-trickle-or-not-to-trickle.695617/post-7454331I don't understand why you indicate that there must "be a slight trickle going down the Emergency Drain". I run a pair of Herbie's in my overflows and gate valves allow me to easily tune the flow to where I have a full siphon on both main drainpipes but zero water going down either of the emergency drainpipes. After a water change, I may have to slightly tweak a gate valve, but that's to be expected. I love the Herbie design...full siphon, zero sound and emergency preparedness!
It will never be perfect so I don't try. Now I don't mess with it at all.