Stant, the vent tube can be underwater, but the water level also has to be above the high point of the main crossover pipe going through the dam also before the siphon begins. Till the pond level rises to force out all the air in the pipe, it will act like a drain. Once a siphon starts, it will continue until the vent tube sucks air.
In short, your vent tube only controls the level the siphon STOPS, while the height of the top of crossover pipe controls when it starts.
Last edited by Rainman; 04/06/15 12:03 PM.
