can someone explain this sump to me

[docta09]

all sumps ive seen have been divided into three (skimmer/refug/return)
looking at this one i dont know how to set it up
i was thinking of putting the skimmer on the right with the water coming from the tank
then from there on i dont know
i have no idea what goes in the red area. i asked the guy and he said thats where he had his downflow go to re reduce airbubbles. whats that
and in the 3rd chamber do i just put a return? seems big

 

[Bifferwine]

It looks like it's plumbed so the return goes out the side -- using an external pump, it looks like.

The water would enter in the red box. If I had to guess, I'd say the skimmer or fuge go in the big compartment, but it would be better if it was separated into different sections for those.

 

[docta09]

If I have a refuge and skimmer to the left and the return in the right wouldn't the water in the fuge just air there if the water enters the middle and leaves to the right