If you build a 2x4 frame with the 2x4's 16" on center it would be the same thing as building a wall. Put a piece of sheathing (plywood) on top for the tank to sit on. I assume you are using an existing wall and have to cut your wall studs out of the way to make the display area. Where you cut those studs you can add 2x4 or 4x4 across the cuts to support the front of the tank (display side) and use the other 2x4's to support the back. As long as it's built correctly a 2x4 can support a lot of weight. On concrete forms we only use 2x4's and there is thousands of pounds of pressure inside the forms. Over kill wouldn't hurt so using a 4x4 for the back legs and possibly doubling the wall studs would be a terrible idea. If you have any questions feel free to PM me