All of those things will still be in the room, so it's not like their weight is just disappeared. They still count, regardless of where they are in the room. Just because they weight the approximate weight of a fully setup 55 gallon, doesn't mean a 55 will work. Those items aren't a "concentrated" weight. They're spread out over different areas. In the case of a 55gallon, that 450 some pounds will be concentrated in a 4'x1.5' space. It's like laying on a bed of 500 nails versus laying on 5 nails. 5 nails is going to hurt alot more, because the weight isn't spread out.



