My water is crystal clear, numbers look great and no algae all summer. But you can see stains that look like dirt or sand or pollen on the bottom of the deep end. The shallow end looks perfect and honestly I’m the only one who probably notices the stains since I take care of the pool. It’s a subtle all over the floor thing, not dark obvious stains. All I can think of is leftover organic (pollen) stains from spring.