Acryllic tank failing???

ya its kind of looking like the welds are giving way. In my honest opinion I would drain that bad boy, clean up the corners and do some weld on #40 pours into the corners.

Ya not looking the prettiest. I would plan a takedown as well, don't think you'll wake up with a flood tomorrow but definitely nothing lasts forever. What is the thickness of the acrylic out of curiosity, as well as the height of the tank?

Look up the weld-on #40 thread, that will help you out huge. You say you havent noticed these before, however wear like that should not happen overnight. If it did happen over the course of a shor tperiod of time I would be concerned, if you just didn't notice that is a difference story. When you put the tank back up ensure it is 100% level.

Post some more pics, other seams would help too.

How thick is the acrylic on the tank? How tall is it and what kind of bracing does it have on top?