When I get called to design a sump for a built-in wall unit, it's tricky. Normal home construction usually won't factor in any type of room to install aquarium filtration and the wall studs are typically in the way. Usually no matter how the stand is built, the sump just doesn't seem to fit. In this case, a small sump (pictured below) was installed to care for the needs of a 340g 8' long tank. After two years, and flooded carpeting too numerous to count, I was asked to build them something new that would help their reef and keep the carpeting dry. They literally kept a wet-vac next to the tank so it was ready to suck up water - that's too often!
As you can see, towels are always handy to soak up excess water. The old sump held 37g to the top, and had to be run rather low to avoid a mess when the main pump is off. Prior to the installation of the new sumps, the plumbing was redone, and an electrician installed the sub-panel on the left.
The new sump incorporates a separate refugium. The sump holds 57g to the top; the refugium 20g. Working in that tight area wasn't fun, and as you can imagine one of the bulkheads was dripping once the new plumbing was installed, forcing me to crawl beneath the tank with a screwdriver and a hammer and tap-tap-tap the nut ever so slightly to stop the drip and not damage the tank nor the bulkhead. Good times.
The main drainline is divided with two drains. The 2" drain pours into the sump's skimmer section. That section also houses 2 Ebo Jager heaters. The skimmer is a Tunze Automatic Skimmer 240/3. It is sitting on a 6" stand. The refugium drains via two parallel 1" pipes into the bubble trap, which pours into the return section. The skimmer zone was built large to house a different skimmer, whenever they were ready to purchase.
The bubble trap has a tray incorporated to run carbon when desired. The eggcrate tray holds pH and ORP probes nicely.
Dimensions: 36" x 23" x 16"
The refugium is on its own stand. A Dolphin Ampmaster 3000 is located beneath the stand. Dimensions: 20" x 20" x 14"
All the refugium needed was 20g of saltwater, which wasn't ready when I took this picture. Lighted with a 28w (output 200w) CF floodlight, macro algae should have no problems growing in this predatory-free environment. A ball valve is visible above the bowl filled with caulerpa, and once opened will provide raw tank water to feed the plants and pods.
I would have preferred to install an even larger sump under this tank, but we used all the space available. The tank above was full of water and livestock, so no changes could be made to the structure/supports.