It's a 5 pound cylinder.
Here was my process since I've owned two marineland tanks with these stands. The first one I raised up on a pedestal. This was great for viewing, but did nothing for the interior dimensions of the stand. Lesson learned.
This tank, I used a router with a plunge bit and basically removed 95% of the top part of the stand. Then I added hardwood 2x2's all the way around, glued and clamped 3 high. Finally I added another piece of 3/4 hardwood plywood back on top (to replace what I cut out earlier), added some chair rail and baseboard trim to cover the 2x2's and painted the stand with my compressor and some oil rubbed bronze paint. Couldn't be happier.
The tank is high enough now, and I have lots of room in the stand!