ASA Glass CO2 Drop Checker

A CO2 checker is an essential tool for monitoring CO2 levels in the aquarium. The CO2 checker is a reservoir designed to contain an indicator solution (not included) and an airspace.

When the drop checker is submerged in the aquarium, the carbon dioxide will out-gas from the aquarium water into the airspace of the drop checker and will eventually be absorbed into the indicator solution.

The carbon dioxide gas will seek a point of equilibrium between the indicator solution and the aquarium water. As equilibrium is achieved, the color of the indicator solution inside of the drop checker will change based on the concentration of CO2 in the aquarium water.