What to put in my DIY overflow sump

[booth2010]

I recently built a 10 gal overflow sump I have a protein skimmer I will put in it (once i find instructions online for how to use), a heater (thats in the tank now), and some chaeto i will be putting in in along with filter floss (i think thats the name). Im not sure what else to put in the sump since this is my first one.
Sump tank: Water enters from the left.

Overflow tube

Overflow tube

Return

500gph water pump (I had a 300gph but was too weak for all the 90deg elbows on the return

 

[booth2010]

1/2" pvc btw

 

[tyler1503]

The only thing I'd add is some carbon in a mesh bag and I'd also keep a specimen container on hand so if you get a nasty hitchhiker you can banish it to the sump till you know if it's beneficial/safe. Without the container it could just hide in your macroalgae and you'll never find him!
I personally can't think of anything else I would add

 

[lemonyx]

You don't really need the first baffle, the bubble trap will take care of that. Maybe a filter sock to filter the big stuff