So yeah the bottom lines are a closed loop. Looks like the top two lines are overflows to the sump.
I guess the other two are returns from the one pump. Maybe he had two smaller pumps but then upgraded to one one pump and had on blocked off. Maybe he slpit the return to two lines to have the flow go differntly.
I guess the other two are returns from the one pump. Maybe he had two smaller pumps but then upgraded to one one pump and had on blocked off. Maybe he slpit the return to two lines to have the flow go differntly.