Herbie overflow question

[ajholms0427]

Just wondering what height I should make the main drain and emergency drain in my corner overflow?

[thegrun]

I like the main drain intake a couple of inches below the teeth of your overflow box. I put the emergency drain at about the middle of the slots.

[kmbyrnes]

I have mine far enough below the teeth that the water falls a bit, but not so much that I hear a waterfall.
The emergency is at the same level as the normal water level in main tank that flows through the teeth.
If something backs up, then it will hit the emergency drain quickly and the noise would alert me to an issue.

[EvenFurther]

The trickle emergency will set the normal water level in the overflow box. You don't want a big drop for noise reasons.

There's different methods for positioning the siphon, depending on that pipe or fitting is used on the intake. Its good to be well below the trickle emergency and normal water line for noise reduction.

http://gmacreef.com/herbie-overflow-reef-tank-plumbing-method-basics/