I cant draw something, take a picture and post it on here so I will attempt to describe my idea.
By using these
6PK 2X4 BASICS SHELF KIT by Hopkins Mfg Corp - 90128MI - More Shelving at doitbest.com
You are able to use four 2x4's for legs, and than several more for the shelving. I came to a total of 43 inches each, for the legs. Which totals with roughly 62" from the floor to the top of the display tank.
-6 inches to account for 2 inches for each of the 3 shelves.
-2 inches for feet on the bottom.
-20 inches for the 29 gallon tank
-15 inches for the 10 gallon tanks
This shelf system allows for at least an inch of access between the top of the tank and the shelf above it. There is extra room above the 10 gallon tanks to allow for a piece of plywood to sit under the tanks for support for the overhang (the brackets only allow for a shelf 15inches deep.
It will also allow you to make the 2x4s for the shelves longer then the framework to allow for side shelves for your supplies; test kits, nets, water chemicals etc.
I will try to get a picture up asap