Free Residual Chlorine Concentration Test Reagent Granule Type, 12 packets ◇ Manufacturer: Kyoritsu Chemical & Co., Ltd. ◇ Expiration Date: December 2026 Many people use this to gauge when to replace their water purifier cartridges. Simply collect water and add this reagent. Testing is very easy. This product was purchased last December. The expiration date seems to be set relatively short to maintain high quality. As shown in the photos, the included accessories are: 1 instruction sheet and 1 copy of the color chart. (o^^o)♪ This is a reagent for measuring the chlorine concentration in water. To use, collect water (10mL) and add the reagent. It will react with the chlorine in the water and change to pink. Determine the chlorine concentration by observing the color. The deeper the pink color, the higher the chlorine concentration in the water. The measurement range is up to 2.0mg/L, which is also usable with measuring instruments. It is mainly used professionally for regular inspections of hot springs and swimming pools. Of course, it can also be used for home pools! Also, many people use it to check if chlorine is removed by home water purifiers. #pool #waterpurifier #hotspring #chlorinemanagement #residualchlorine #DPDreagent #DPDtablets #reagent #residualchlorinetestreagent #residualchlorinetestreagent #aquarium #residualchlorinetest #homepool #watersports #seasonaltoys #swimring #float