Here's the deal. The Nano Cube has been having a problem cracking at the seamless corners. The problem is a combination of engineering and packaging errors but predominantly...too thin glass. The cracking mostly occurs with the tank I have, the 24G. The 12 and 6 are less likely. My advice is:
1) If you must have a 24G, DO NOT ORDER IT OVER THE INTERNET OR HAVE IT SHIPPED. If you do, put on thick gloves before you reach in the box to pull it out
2) If you must have the cube, buy one at your lfs and have them open it there. Inspect it all over including under the frame. Keep your receipt and know what their guarantee/return policy is. There still have been some latent cracks.
3) Better yet, look at the AquaPod or, if you can wait, the Nano Cube is reportedly being improved and re-engineered very soon. You could call JBJ lighting and see if they have a release date. SH