The Up Aqua CO2 Long Term Monitor Reagent is a liquid test kit designed to measure the concentration of dissolved carbon dioxide in aquarium water. It provides accurate readings for up to two months and is suitable for freshwater and saltwater aquariums. The reagent also helps to ensure successful plant growth, as CO2 levels are critical for photosynthesis. The kit includes a color chart that makes it easy to compare the measurements to the optimal range for aquariums. The reagent is easy to use, economical, and accurate.