I have tested several times and finally believe it. My pool's Cyanuric Acid level is between 85 and 100, so I am going to drain half my pool before the swimming season gets started here. I will also quit using Leslie's 3" pucks and start sanitizing with Chlorox. I have a submursible pump set on the bottom step. I'd like to drain even more out, thinking I need to remove most of the water in the shallow end to achieve a 50% reduction. Will it damage the vinyl liner to set the submrusible pump directly on the liner?