RFL...covering your outlet DID "fill the outlet" and there was enough velocity to draw out the remaining air from the now filled outlet side. It may be more just terminology, but there is NO seal from the elbow at the end with water. It is there for fluid/air dynamics...the upward turn of the elbow makes it impossible for air to enter as air will not "sink" into the pipe. A siphon can not just be turned on by simply covering the vent tube unless all conditions are met for a siphon...it CAN be turned off by allowing air to enter.

If your vent tube was capped, and you were able to hand cover the outlet, I would fear the outlet side of your system is not sealed air tight because the pipe would not have compressed the trapped air fully filled, if sealed.


Regardless, you got 'er going and that is what was important.

Last edited by Rainman; 05/05/13 04:48 PM.