My old tank was 48" long, 18" deep and 24" tall. Each dimension was CLOSE, but not quite what I wanted. So this time around I went with the largest dimensions I could realistically want and also importantly, FIT into my little basement. The new tank is 72" long, 24" deep, and 31" tall. And just barely fit into the basement.
As I was redoing the basement, I realized "Wow, this is where the tank should go!" Up until then, I'd planned to tank over a substantial part of the dining room above, reinforce the floor, run additional power, etc. But the basement was a blank slate, already reinforced (it's concrete!) and was all found space, so no stealing living area from the other inhabitants of the house.
So I immediately tore out the studs I'd begun adding for the wall between the playroom and the storage room, and began to design and construct a built-in stand:
Here's the hole in the wall, drywalled (but not yet spackled or painted) and ready to receive the tank:
Moving the tank into place turned out to be... Challenging. I had three guys helping me, but the total weight of the tank was well over 400 pounds, and the thing is delicate and unwieldy. We could not lift the tank outright, but we could lift an end of it at a time, so we could lower the back out of the car, then lower the front. I'd tacked carpet onto sheets of OSB to make sleds, and those proved to be our salvation. We were able to get the tank from the one in the car onto one on the driveway, then walk that sheet over to the side door of the house, then put the one from the car as a ramp into the door, etc. It was quite a process.
In that second (top right) image, you can see the carpet ramp and the painted/unpainted shadows of the two steps I had to remove from the basement stairs to allow the tank to enter the building. Prior to ordering the tank I'd made a mockup with the same dimensions, and moved it from outside to inside, and dimensionally, it worked. However, I did not take the weight into account, and it wasn't possible to move the tank through the same motions when the real day came. Live and learn there. The third image (bottom left) is the tank sitting half on the ledge of the foundation wall, half on a 2x4 brace I'd made for just this purpose, as a staging step prior to the last push, getting the tank onto the stand (last picture).
I've since replaced the steps, here they are a day or two later:
Once the tank was physically in place, I began building the wall above the tank. I didn't want the wall to impede the lighting entering the tank, so I built the bottom of the wall at an angle, shown below in various stages of being built and drywalled: