The sock pipe is used only for the water level to the vent. The only water that exits the pond from the sock pipe would be what is sucked up the vent. This works like any siphon system only the vent is below the ground level. Instead of running a vent back to the pond, I brought the water level inside of the dam. This way it is out of the way of mowing, and frost proof.
nehunter, the length of the sock pipe is not crucial, I just used what I had and covered it with gravel. The sock pipe is not an intake for the siphon system. It only allows the water level to reach my vent.
I have posted pictures of two siphon systems from two different ponds on this thread. In the second picture from my original post, I had two 6 inch pipes connected with a tee as the shared vent. In my last picture posted on 12-3-2019, I have cut out the tee and put two separate 2 inch vents and concreted the bottom and laid block up to a irrigation box that I purchased from Lowes. You can see the water level up to the two separate vents.
