Yeah, dwzm hints at the trick, the 55 is the same length as the 90. It makes stand design a little tricky if you catch my drift. It just makes it look a little bulky because you have to extend the width out a little bit, and also you usually have to build the stand around the sump tank, so it doesn't come out. If you think creatively you can do it though. If you don't feel like thinking, a 30g tank fits nicely under a stand for a 75/90