Hey 85, whats your plan, are they side by side or stacking, if its side by side go to www.garf.org, they got great planners there, you punch in your size and they give you instructions and a cut list.
I had 2 75gals. together on one stand I used 8 4x4s for the legs and framed the rest out with 2x4s it worked great. i had it set up for almost 10 years. . here is a pic of my 300g stand it is a bit overkill for your application but you'll get the idea