As a plumber I have installed a few septic tanks with self priming siphon systems. In the image below where the pipe touches the base of the root tank you can notch the pipe so it is not sucked in to the base and restricting the flow, breaking the siphon. Where the drain pipe leaves the bottom of the root tank it can be reduced to one pipe size smaller to assist in the siphon action.
I am still an amateur so would like input in to this by the pros here...
