Great questions
TheWolfman
I am also going through a similar struggle. Here is a pic of a sump that I recently picked up
So this sump is designed to have the overflow enter the chamber in the back corner with the black arrow. Then overflow into the sock catchers noted by blue arrow, then flowing out the bottom with red arrow.
The baffles on the other side of the sump are basically just to stop bubbles from being sucked into the return pump. I am toying with the idea of using floss at these returns as well, because I may have some fish growing out in the big middle chamber.
Other ideas that I have had are to add k1 to the overflow chamber to simulate a small fluidized bed (add a strainer at top to prevent k1 in the socks). Also possibly adding floss inside of the socks to lengthen the lifespan of the socks (in theory), and pack as much bio media anywhere I have any room without causing flow restrictions.
All of these plans are just theories atm. I am planning to set this up and have it running possibly by October (ish). Don’t know if this is helpful for you to get an idea, and not trying to highjack your thread, but if someone has feedback on my ideas it might help you with what you want to do.
Hth