The sump is divided up into four sections with baffles. The drain & pre-filter (filter socks) section is also divided up to contain the drain from the tank and two 4" socks). That section is also where I dose my 2 part and top off. There is the skimmer section (which also houses the manifold pump), the return pump section and then the frag tank on the end. It probably wouldn't make any difference what my dimensions are, since it was pretty much built with the equipment I had in mind - except for the skimmer. I ended up upgrading the skimmer and then had to find one that fit the same footprint as the one I had - which was already small. Having to find a good larger skimmer with the same footprint as your smaller skimmer is not easy.I want your sump dimension plans man, simply the best organized sump ever