Dennerle Long-term CO2 Test

The CO2 long-term test Crystal is used for permanent CO2 measurement in freshwater aquariums and is available in two different sizes.

With the CO2 long-term test Crystal, you can permanently measure your CO2 content in the aquarium water. To do this, fill the indicator liquid into the crystal and install it, once turned upside down on aquarium glass. The liquid changes colour after about 30 minutes and shows you whether the CO2 content is too low, optimal or too much. Occasionally you should renew the indicator fluid.

Tip: If you really want to get the most out of your plant aquarium, combine the CO2 fertilisation with the plant elixir and the NutriBalls!

Our expert Oliver Knott recommends:

The best CO2 supply is nothing unless you check it regularly - with the long-term test you can see at a glance whether your supply is also in the green area!