Old acrylic sump design

[xxcaptainsparklesxx]

I just bought a new to me 120gal display with about a 20 or so gallon sump. This thing is ancient. It has a Durso overflow. I have questions regarding the sump layout and how to get mechanical filtration in there, ie filter socks.
I will attach a video so you guys can see

 

[Fish Fan]

Welcome to Reef2Reef!

#WelcometoR2R

I'm not an expert on sump layout, but you might try using something like this to hold your filter sock in that first chamber right where the Durso drain comes into the sump:
Filter Sock Holder at BRS

Then, and this is just a guess, but you could cut something like plastic egg crate (lighting diffuser) to rest on those tabs at the bottom of the other sections, then you could place media bags or other filter media on those egg crate shelves.

The R2R #reefsquad may be able to help with further suggestions

Good luck with your build!

 

[Pntbll687]

So, pause the video at 26-27sec. You can see the "tabs" on the baffles. Cut a piece of eggcrate to sit on the tabs. Then use a filter pad or filter floss on top of the eggcrate.

I would use a filter pad like this
https://www.aquaticexperts.com/prod...T1kAGcMrQkNYevtY29uyzi&variant=43646719459564

If you wanted to use filter floss, you might need something a little finer than eggcrate to hold the floss. Get a scrap piece of acrylic or lexan from a local hardware store, drill a bunch of holes. Lay the lexan on the tabs and filter floss on top of it.

 

[Fish Fan]

If you want to run filter floss, I'd swap the sock for a media cup, then load that with Poly-Fil, which is the same as aquarium filter floss, but much cheaper:
Media Cup

Poly-Fil stuffing

 

[Rocks reef]

The filter sock holder and the egg crate with filter floss ideas are both solid advice. In reality, you don't even need to run either of them. However, the two ideas mentioned will get you to the goal you are trying to achieve.