my 620t cracked in the curve last year no fish died so all good. I thought it was because I bumped it cleaning the filter but if they are cracking regularly you have to wonder. The local shop where I purchase my fish didn't know anything about tanks splitting so I was able to claim insurance and got a new glass body which was $300. I had to pay an excess but the insurance paid to clean up the carpet in my bedroom which had to be lifted and dried out. I am now abit worried I could have it happen again.