I realize this is an old thread, but....I have a buddy who's Bashsea acrylic sump started cracking randomly just like this. He was wondering if it could have possibly been caused by either 1) cleaning with vinegar/water solutions or 2) potentially from UV (he has a UV light sitting in his sump that he uses for sterlization). Any thoughts from anyone?
Or maybe it was just a bad piece of acrylic when the sump was manufactured as the thread says above.