One system counts as one tank, I've won that wife argument.This idea was born from a the "in wall loophole". When your better half points out that large reef tanks tend to crowd a room up - you can use the "in wall loophole" - which - by definition puts the tank in the wall, and therefore, not crowding any room whatsoever. Now, if you build a wall that is four feet thick - you have some serious options. I was able to get this past not only my wife, but also the real boss, our interior designer.
Kidding aside, our friend and designer helped me with the dimensions and came up with some cladding ideas for the cabinet / wall, which I think will be unique - and will coordinate with the surrounding decor. Putting this in the control of our designer - has done a great deal to alleviate stress.