Review this explanation of the bottom withdrawal siphon system (note its points are labeled differently than your drawing):

http://www.georgialandsales.com/pdf/PondSiphonSystem.pdf

It states point B should be at least one pipe diameter lower than point A. Also C should be at least 4' below E.

Does your system meet this? If not I suspect your pond will need a higher "flood" to activate the full siphon mode. More air trapped in the top of the system will have to be "sucked" down to go into siphon mode.

And yes, the majority of the year the pipe will be running in "standard" mode. Just during peak heavy rain events it will run in siphon mode.

Last edited by Redonthehead; 05/28/19 11:21 AM.
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