i am currently looking at purchising a new 75 gal rr tank. I have 2 options as where to put the overflows, 1 in the corner or 1 in the center of the tank. it seems that one in the center would give more uniform surface skimming. what are your opinions on this and i would also like some detailed plans on building a sump from a 20 long. any sugestionswould be great. thanks in advance.