How did the one 16" end up working out for you? I've had some people say I should run two for the additional surface skimming as well as to keep it quiet. I really don't want to deal with all that plumbing if it isn't absolutely necessary. I just placed my order for the 240g tank and asked them to drill for two overflows in the middle of the back panel, and now I'm seriously considering having them only drill for the one. Before I modified the order I was hoping to see if you already have yours set up and how it was running for you. I appreciate your help!