Wow I am not at all trying to be rude, but you are comparing apples to a brick. [smilie=whew.gif] Why I am new to the saltwater world I still don't have a complete grasp on all of this either, but a lot of what you are asking can be found here http://www.melevsreef.com/what_sump.html . I would read this page and most of what you are looking for can be answered. You are comparing mechanical filtration to live filtration with some mechanical filtration with a sump. Please read this in detail it took me about 3 times to understand it fully, and I am still a little baffled at time. Crazy how much it takes to build and maintain a small echo system for fish to live. God sure had his hands full when he created us!