CO2 Test Kit

The CO2 Test Kit uses a sodium hydroxide drop-count titration to estimate dissolved carbon dioxide in aquarium water. Accurate CO2 management is critical in planted aquariums: too little CO2 limits photosynthesis and plant growth, while too much depletes dissolved oxygen and suffocates fish.

The target CO2 range for planted tanks is 20–30 ppm. The test is performed on freshly collected water with minimal agitation to prevent off-gassing before the test is complete. Each drop of reagent consumed represents a defined CO2 increment, and the endpoint is marked by a colour change from clear to pale yellow.

The test kit provides a useful spot-check to complement permanent drop checker monitoring and helps calibrate injection rates when setting up new CO2 systems or after adjusting regulators.