The sump has seven sections. Starting on the front left side, the first section is one of two 10" x 10" x 12" bioball sections. Each side holds 1000 1" bio balls leaving about 2" on top for filter padding and a drip plate. 
Directly behind that is the second section which will be used for an auto top off and additives. This section is only connected to the rear return section by a few small holes. This will keep the water smooth around any level switches or additives. Third, in the front center is the waterfall for the return section. There are two waterfall baffles, one for each drain. The baffles are 13-1/2" tall with 1-1/2" tall x 5/16" wide fingers cut out of the top ( 12" to bottom of fingers). 
Having this section in the front allows me to easily see the return water level. In between the baffles is the bubble trap. Instead of having two more baffles parallel to the waterfall baffles running full width, I elected to have a horizontal plate separating the front and rear of the return section. This configuration uses one bubble trap in the center, allows more room in the pump section, and uses less acrylic. The fourth section is the pump return area. It runs along the back of the sump and 
underneath the rear of the refugium. I am currnetly running a MAG 9.5 for the main return, and a Gen-X1000 for the refugium. The fifth section in the right center is a freshwater refugium. It sits 6" above the bottom and runs the full width of the sump. This allows for the refugium pump to be run underneath in the rear, and allows water from the right side drain to flow below it in the front. The refugium measures 12" x 16" x 16" and holds 12.1 gallons at its normal operating level.
It has a 1" cut out on the top of its left side wall. This keeps the refugium from overflowing the top of the sump if the drain should ever clog. The inlet pipe is 3/4" and the drain is 1" clear pvc. Since the refugium will be filled with plants, the drain is going to get clogged up from debris from time to 
time. A clear pipe allows me to see the water flow going through it and also see clogs in the pipe when they occur. The sixth section in the right rear corner is a dry compartment. There is not enough room outside the sump for a CO2 bottle, so this area will be used for holding a CO2 system. 
I plan on using two alternating 3-liter soda bottles as CO2 yeast generators in this compartment for now. The seventh and final section in the front right corner is the second wet/dry bio ball area for the right side drain.
Check out the step by step process of this sump being built.
