Displays the rate of CO2 injection. Discreet design. Suitable for all aquarium sizes. Simple and easy to use. The bubble counter is a straightforward and elegant tool for monitoring the CO2 injection rate in planted aquariums. This bubble counter is placed in the CO2 supply, reducing the visibility of the CO2 equipment in the planted aquarium while allowing for easy monitoring of CO2 production at any time. Compatible with 6 mm hoses.