Disposable CO2 in the aquarium
If invertebrates are kept, the CO2 content of the water should in no case exceed 30 mg/l, 20 mg/l is better. Then the gas exchange in the gills works smoothly. If too much CO2 is dissolved in the water, the animals cannot get rid of the carbon dioxide from their blood. In the worst case they can even suffocate. A CO2 system is therefore not suitable for lowering the pH value without restriction, even though this is recommended time and again. The CO2 content is monitored with a continuous test or dropchecker.
Structure of a disposable CO2 system
The carbon dioxide is stored in the pressurized gas cylinder under high pressure in liquid form. Only a small part evaporates and lies on top of the liquid. The pressure reducer is screwed onto this pressurized gas cylinder. Compressed gas cylinders may only be operated in an upright position so that no liquid CO2 gets into the pressure reducer - this would destroy it! With the pressure reducer, the CO2 output can be controlled and adjusted very precisely. A special CO2-tight hose leads from the pressure reducer to the aquarium. Normal air or silicone hoses are unsuitable here, as CO2 has very small molecules and too much would escape through the conventional hose material. To prevent water from the aquarium from entering the pressure reducer, a check valve is installed in the hose. In a complete set, everything you need to supply CO2 to a planted aquarium is already present.
It is important that the CO2 gas has as much contact with the water as possible. Therefore, it is not simply allowed to bubble into the tank, but the bubbles are directed through a diffuser or a flipper. There the bubbles slowly move upwards and dissolve completely in the water during this time. Any false gases are discharged.
The bottles of disposable CO2 cannot be refilled. They are disposed of via household waste or the yellow bin/bag. Disposable CO2 systems and reusable cylinders cannot be easily combined. If you want to convert your disposable CO2 system to reusable cylinders, you will need a suitable adapter.