I'm of mixed opinion with the socks. I love to catch the gunk and remove it manually with the sock but I also hate catching things that are beneficial such as pods. About two months ago I removed the socks and now I only use them when I'm doing a water changing (or some other maintenance where I'd be stirring up gunk). Water clarity has remained excellent without them (and it's certainly less maintenance as I was switching them roughly every three days).
As for the sump itself, I think skimmers are best placed in the first chamber of the series as this gives the most time for micro bubbles to diffuse. The sump posted above has about 10.5" in the skimmer chamber and 13" in the refugium chamber followed but a 1" bubble trap and and 5" return chamber. In the end, I'd like a few more inches in the first chamber so I had a little more room for a skimmer with a larger footprint. I have the skimmer, heater, probes, and pump to the carbon reactor in this chamber.
As for the sump itself, I think skimmers are best placed in the first chamber of the series as this gives the most time for micro bubbles to diffuse. The sump posted above has about 10.5" in the skimmer chamber and 13" in the refugium chamber followed but a 1" bubble trap and and 5" return chamber. In the end, I'd like a few more inches in the first chamber so I had a little more room for a skimmer with a larger footprint. I have the skimmer, heater, probes, and pump to the carbon reactor in this chamber.