Will the PVC overflows work in a half filled tank?

[Michiba54]

My tank is a 20 long with 6" off water an I want to add an over sized sump to increase the water volume.

Will PVC overflows work? I made a crummy blue print in MS paint...

 

[JK47]

I have done it before with low turn over (200-300 GPH). I have never tried it at a larger GPH ratio though.

 

[Michiba54]

Made a dry fit model to day an it doesn't wanna hold a prime... might just be an excuse to buy a glass hole kit

 

[sross]

as long as air can get into the line you wont be able to hold the siphon. You would have to forget a vent and the overflow and move the pipe below the water line. The exit would have to be below the start a good deal in order have a good water flow.