Ok so my plan is 3-4 4" socks....

Next question, should they be in the water or out? Or half in & half out?

Top rim of sock slightly above water level so that when it get plugged up water can just run over the edge into your sump.

The 200M rectangular filter sock by Eshopps will last about a week before needing to be swapped and it's synthetic so it's strong. But because I've learned to allow microorganisms to flow right through the sump 20hrs a day to feed the dt's sponges and gorgs, I have a tee that's directed both to the sock and the skimmer chamber. During feeding, I close a valve and all the flow is directed to the sock and keeps the sump clean...great DT polisher too.

My plan is to have the tank water empty into an area thats baffold is 2 inches from the top of the sump, this chamber will have chaeto in it. I am planning for the returning water to stir and swirl the chaeto...

Then when it over flows that baffold there is a flat shelf that's about 6" long with a 1 cm high water stop at the end. In that flat shelf I will set the 3-4 4" holes for socks so water can just flow down into the sock into the next chamber. If it over flows it needs the 1 cm of flow to go over the water stop and overflow into the next chamber unfiltered....