Not too impressive is it? I found it while googling worlds best tanks.
It was among the toilet tank, two tanks connected by a bridge spanning across a room(also not very impressive). However there was a 15 story 270,000 gallon SW
tank in a hotel lobby in Germany with an elevator lift in the middle! It employs 2 full time divers to care for it.
There is also a "Infiniti Tank" that filters by flowing up over all 4 sides into a return that pumps back into the tank that was pretty sick!