so I finally broke down and bought some black foam to give my 90g tank a background. Easy to size and install....but upon installation I notice something that looks like a crack, check it out as best as I can and as far as I can tell it’s on the outside....pretty sure I bought the tank with this mark on it just didn’t notice as I didn’t have a bkg for the tank.
Now I’m worried that it will extend and cause me to have a tank fail...what do you think? Surface enough not to worry or too deep and would get new tank? What would you do?
Pic attached (yes I know there’s algae on the glass, I don’t clean it off the back wall, but did clean the cracked area)

Now I’m worried that it will extend and cause me to have a tank fail...what do you think? Surface enough not to worry or too deep and would get new tank? What would you do?
Pic attached (yes I know there’s algae on the glass, I don’t clean it off the back wall, but did clean the cracked area)
