Alright this may be difficult for me to explain but i'll give it a stab.
Use a 20L. From left to right, start with the refugia, make as big as possible. Cut a peice of acrylic to about 1/2"from top of tank. middle section is used for your skimmer, right section used for return. Make sure you have about 3 or 4 baffles b/w the middle and right sections. This is the key part, tee your drain line. One end of the tee goes to the refugia and the other to the middle section. Place a ball valve on the line going to the refugia so that you can regulate flow to it. IMO you should feed your refugia clean, unskimmed water from your display. At the same time, this set-up will allow you to regulate the amount of water going into the area so that you don't flush your pods and stuff out of the refugia. A lot of ppl design there sumps to house the refugia in the middle section, not a good idea because you can't regulate the amout of water passing thru it. Not sure if that helps, but good luck n e ways.
Cheers,
Kurt
75gal rr 30gal sump. 6X54w t5 ATI/GE bulbs with tek II reflectors, CA reactor, chiller, reef devil skimmer, close loop to om super squirt. FUN!!
Location: I live on the Fish Hatchery in Uvalde. I work as a fishy biologist.