The Fluval Ceramic CO2 Bubble Counter is ideal for use in planted nano aquariums, including Fluval's Flora Aquatic Plant Kit. The Fluval CO2 Bubble Counter is a replacement part for the Fluval 88g CO2 Diffuser. The diffuser helps to effectively dissolve CO2 into your aquarium, while the Fluval CO2 Bubble Counter provides accurate monitoring of the CO2 dosing.