sump

i think most people have them in the middle... first chamber is intake, second refugium, then third is back to the tank... and leave it open for better air/gas exchange. and if you ask Mark he says the simpler the better

As always, the bigger the better and a deep sand bed is generally preferred as well. make the refugium as high and large as you can but keep in mind you'll need to get your hands in there from time to time and you'll need some sort of lighting above it as well. 

I have a 55 gallon sump as well. I run my refugium before my skimmer. In my sump it goes like this: Water comes in from the overflow and is split into 2 outlets; 1 feeds into the refugium which is a 20 gallon rubbermaid tote w/ 5 1/2-6" sandbed LR rubble and lots of macroalgae of various types where it will then spill over into the sump. Above the fuge are 2 17w normal flouresent glow lights from Home Depot. The other outlet spills directly into the larger compartment of the sump where the skimmer, UV, and AC reactor are located. This way about 1/2 the water is getting fed into the fuge where the unfiltered water full of all the good stuff feeds the fuge before it heads into the skimmer, UV, and AC to be "cleaned". It is then pumped back up to my display at about 1300gph through two different outlets on opposite ends of the tank. Using this setup I have never had any issues at all. I also don't run filter socks except after a water change. Hope this helps!

Edited by CapnMorgan - December 06 2009 at 2:05am

Thanks everyone for the help.  Now it is time to build.

dirt from back yard?