Co2 Level Indicator Liquid CO2 Indicator reagent is used to monitor approximate CO2 levels and also helps gauge CO2 levels in aquariums. Includes a 10ml fluid CO2 Indicator Liquid. The CO2 reagent is filled into the CO2 Drop Checker and will change the color according to the amount of dissolved CO2 in the aquarium water. Green will indicate a proper CO2 value, yellow will indicate too much CO2 and blue will show not enough CO2. Key Features: Monitors levels of CO2 &PH in aquariums, Suitable for all kinds of fish tank Ensures fish and plants live in a healthy environment Provide maximum reliability Provides accurate dosing of CO2 Different color of liquid represents the different concentration of CO2 Fast response time. Use to measure CO2 levels at-a-glance. Package Includes: 1x Co2 Level Indicator Liquid