The CO2Art Aquarium CO2 Drop Checker Solution 15ml is a pre-made 4dKH solution that contains the appropriate amount of indicator.

It is used with the CO2 Drop Checker and it is recommended to replace it at least once a month to maintain measurement accuracy. It is easy to use, no mixing required. Simply open the cap and fill the CO2 Drop Checker.

• Fill the drop checker 2/3 full with CO2 Drop Checker solution.
• Install the drop checker inside the aquarium.
• The optimal CO2 level is achieved when the indicator solution is deep green.

When the Drop Checker is submerged in the aquarium, carbon dioxide will diffuse from the aquarium water into the air space of the drop checker and will eventually be absorbed into the indicator solution. The carbon dioxide gas will seek a balance point between the indicator solution and the aquarium water. As equilibrium is reached, the color of the indicator solution inside the drop checker will change based on the CO2 concentration in the aquarium water.

If the indicator solution is green, then there are appropriate levels of carbon dioxide in the aquarium and no action is required. If the solution in the drop checker turns blue or yellow, then the CO2 levels in the aquarium are too low or too high, respectively.