Crack in my sump.....

[Coralgurl]

Noticed I have a crack in my sump. It's located in my ato reservoir, but is only separated by glass inside from the rest of the sump. I can feel it on the outside of the tank, not the inside. The crack is on the backside of the tank and starts on the bottom. The sump is on foam, not sure how this happened, there's nothing there for anything to hit it. It's not leaking so not sure if I should be worried? I'm going to mark it to see if it continues to move.

I can not get this sump out of my stand, without completely emptying the tank so any advice is welcome to prevent a disaster.