At first when I saw the offset between the bottom and 2nd tanks I wondered why that nifty space wasn't used for small shelving, up until the right side of my brain slapped my left. Your offset design completely solves the issue of the extra room needed for stacked tank access I have been wrestling with. I also like that fact that you left some room at the bottom as I hate the thought of bending too far down as appose to having to go up.
I think I'm going to use your basic designe and build it modular, first the bottom (try it on for size) and then the 2nd top tier a day later. Only for my sanity becasue if I try to do it all at once I will run into proportional designed issues. But I think Im sold, I just hope my wife will be when she returns from Taiwan and sees it and another tank LOL.
Thanks Im copying these photo as well into photoshop so I can use the block background to get proportions and blow up the pics, Thanks sooo much.