CO2 Indicator solution refill 15ml, for use with CO2 drop checker. Aids in CO2 monitoring by changing colour depending on the concentration of CO2 in the aquarium.
Directions: Ensure your checker is clean. Add 15 drops of CO2 indicator into the checker and make sure it is stored in the bulbous side of the valve with the opening facing down. Attach this to the side of your tank, completely submerged in the tank water. Check after 2-4 hours.