Taylor 2000 Series Comparator, Bromine, Chlorine, pHThe Taylor 2000 Series Comparator, Bromine, Chlorine, pH is a replacement test tube unit that is included in most K 2000 Series Water Testing Kits. Using a Comparator in good condition is important to make sure water tests are as accurate as possible. If the Comparator is not sealing properly or leaks, it is best to replace to make sure pools are accurately tested.