If you decide not to stop by here are a few more tips.
#1 increase the dimensions by a 1/2 to 3/4". The frame on tank is not 72x24, its larger. This will also allow you to attach trim around the whole stand which will hide the top of the plywood and even the whole tank frame. A little higher an you can cover some or all of the sand bed if you're not going bare bottom.
#2 When I say laminated plywood I mean two 3/4" ply's glued and screwed together. So on the inside, run a second 8 to 10" strip around the whole upper part of the stand. Then in the corners, on both inner sides, run a 3" wide kicker all the way to the bottom.
#3 Use Titebond III on all joints and seams. The screws initially hold it together but the glue is where the real strength comes from.
If built this way it will be more than strong enough to hold much more weight than you're going to put on it. You can also cut out a large opening on the front side, the back too if you wanted. The opening can be from kicker to kicker and up to the bottom of the upper strip. With two doors opened you'd have almost full access to the space under the tank.
Good luck on the build!