But wouldn't you want that? It will pull the water from the display tank and keep it silent at the same time. The issue would be if you restrict it too much and the return overcomes the drain.Decreasing the amount of water going down the single drain will raise the level of water in the overflow. When the drain is far enough under water, it will act as a siphon. Air will no longer be in the drain, and it will be silent. That's how reefers set up a Herbie or Beanimal drain system.
Yes, you need the emergency/trickle pipe to make it safe. Without the emergency/trickle drain, any blockage (even a partial one) risks flooding the display.


