Taylor DPD Reagent #2 Dropper Bottle, 3/4 oz | R-0002-A

Taylor formulates its reagents to maintain effectiveness for at least one year, with a few exceptions, such as molybdenum indicator in liquid form, which should be tested against a standard after four months. As a general precaution, replace all reagents that are more than one year old, or at the beginning of a new testing season.