CO2 Indicator List Grid CO2 Indicator – All Angle View CHARACTERISTICS: Allows you to monitor the CO2 level in your tank from any angle. Unique design prevents any chance of spilling the indicator solution. Reusable color chart sticker allows the constant repositioning of the position of the label on the aquarium. ... View Details Solution of CO2 Indicator CHARACTERISTICS: Simply inject 1CC of CO2 Indicator solution into the cap of CO2 indicator. Adding aquarium water is not necessary. Recommended to be changed only once a month. Not necessary to change solution every time a maintenance is done to the aquarium. ... View Details Share