OK, so the sump is a converted wet/dry (by previous owner) so it is a 2 chamber.
Fuge side with overflow pouring in the top. I have fuge mud in there some LR rubble and Chaeto. Lots of critters in there, sponges, stars, pods and worms.
It overflows into the Sump side (I got to clean that return tube!
). My protein skimmer is in there and a bag of carbon. There is also a grounding probe in there.
Here is the skimmer... AquaC Urchin.
Next to that is my overflow reservoir. I use an ATO by JBJ. Highly recommended.
Here is a "fullish" shot.
And finally my DIY return with ball valve to adjust flow.