Here's an old video of my 240 cube rimless when it was a saltwater tank. Its 4'x4'x2', 1" thick acrylic all around.
http://s3.photobucket.com/albums/y90...funder20Ks.flv
Its now a freshwater discuss/tetra tank and looks like this:
But I may be replacing it soon with a 525 gallon concave 10 footer that will be saltwater again.... maybe.