That shows water trickling out of the emergency. The water is only a 1/2 below the wier. Even if you want to run a dry emergency you raise the water level in the overflow box by closing the valve on the main drain. It shows an animation of it. The 6 inch gap is between the emergency and the main drain to help the siphon start. I heard people say it works fine with out that gap but I can't say that for sure.
It's all in the article. They even have a picture of it.
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Last edited by SFish; 11/07/2017 at 12:11 PM.
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