i am sumwhat worried about the same thing. i was doing a little research on nano-reef.com and they had a poll, almost 20% of the JBJ Nano cubes that members had cracked. it was random on the number that were out of the box and over a period of time. my understanding is that the 2006 models have thicker glass, so they would be less prone to cracking. also the 6 and 12 gallon are less likely to crack, but they have for some people.