Pond Boss Forums POND CONSTRUCTION Building a dam Water Level - Siphon System

I just installed a 10" siphon system on my pond. I placed the horizontal pipe through the dam at the maximum water level for the pond. I have been playing with the vent height relative to the horizontal pipe.

So Im a little confused. I read someones post that if I want to lower the pond I can just lower the position of the vent. I can see this to a point, but I dont seem to follow the physics once you lower the vent below the horizontal pipe. I thought it was the gravity of the water flowing on the backside that creates the suction. So if there is no water in the horizontal pipe but yet the vent is lower than the horizontal pipe, how is it possible to start a suction? If this is the case I cant see that water would flow.

I believe you would need to cap the outflow end and manually fill that section of pipe. Then either cap the vent, or run the opening down to the desired depth. When you open the outflow end (do it quickly), the water in the pipe should be enough to pull the siphon and run until the vent can breathe again.

I am no expert, so take my comments with that in mind.

I have a diagram of siphon pipe that we use to install them. I'm pretty sure Lawn Dart is correct on what he is saying. I have seen the vent pipe with a valve on it so once the siphon has began you can let it siphon until you turn the valve back on. If you would like a copy of the diagram my email is derrick@adamslandimprovement.com