My tank that I just set up last week is off by about 1/2 inch from side to side, and maybe 1/4 inch front to back, too. I figure that I should get it leveled out pretty soon, but is there really a reasonably good chance for the tank to spring a leak or crack like this?
I wouldn't say it is a good chance... but I would err on the side of caution and get it fixed sooner rather than later. I am fixing mine tomorrow night. I took out about 20 pounds of the live rock and 33 gallons of water. At most there is 40 pounds of sand, 7 gallons of water and 20 pounds of rock left. I didn't want to chance it. Figured I would be safe for now if I removed a majority of the weight.