Ghost overflow 21" external box help

[dvybiral]

Hello Reefers,
I need advice on the external box of the ghost overflow , not filling to achieve full siphon. I have a 120 gal. Reef Savvy tank with the 21" ghost overflow, custom 46 gal. Geo's Reef sump, Cor-20 pump. the plumbing is 1" PVC and the tank is drilled 1" single return. See photo's I have attached.
Thank you in advance for any help.
DV

 

[Smprc]

Have you closed the gate valve? I have the 16 inch. I am pretty sure you just need to start closing the gate valve. The water level will start to rise in the overflow external box. Then you will start to open it until the level is just barely over the open line, it will take time to settle.

 

[Smprc]

Also, why do you have 2 u pipes. You should only have 1. They might have changed it, but as far as I know you just need one u pipe and 2 straight pipes, one for emergency and other for the trickle.