Hey bob don't confuse sump, and refugium. A refugium s a place with little water flow. This allows for your macro to grow,copepodsto run freely, and also a place of "refuge" for say a healing starfish, or a great place to frag corals that need very low water flow. In the fuge on my 90g I am running just a fuge, with very little flow through it, but I will be adding a sump, filled with lots of live rock for filtration, and probably a part time skimmer. If you do a Fuge search, or check out Broomer5's web site you can probably get all the answers you need.