Hi, we have an L shaped new pool with a 12x12 sunshelf (12" deep). When we were wading in the water, my husband notice a substantial foot sized lump on the floor in one of the quadrants. It's noticeable enough where a chair wouldn't sit level when placed in the pool. We aren't sure if this is a normal variance with a sunshelf this size or if it was a mistake that needs fixed before we move in. Any advice would be appreciated.