No amount of chemical treatment would keep the water clear without a filter. When operating properly, a filter will remove virtually all particulate matter from the water. These particles of dirt and debris are the result of environmental fallout or are left behind by the bathers and, when not properly filtered out, will cause the water to become hazy and cloudy. A good filter that is well maintained and properly functioning is what will give the healthy water a crystal clear look for your pool with less chemicals required and better flow.