Complete™ kit for Chlorine/Bromine, pH, Alkalinity, Hardness, CYA (DPD–high range) (.75 oz bottles). Taylor formulates its reagents to remain effective for at least one year, with only very few exceptions (molybdenum indicator in liquid form is one; after four months old it should be tested against a standard periodically). As a general precaution, replace all reagents more than one year old, or at the beginning of a new testing season.