Paffrathsche Rinne
The Paffrathsche Rinne (also: Paffrathsche shell, Paffrathschale) is a simple device to dissolve carbon dioxide (CO 2 ) in water. Its origin and its most common application is in the aquarium hobby , where it is used to supply organically produced (through yeast fermentation ) CO 2 . It was named after its developer or first descriptor Kurt Paffrath , an aquarium non-fiction author. CO 2 serves as an important plant nutrient and also influences the pH value of the aquarium water.
construction
An upturned bowl, which is mounted below the water level in the aquarium, for example, using suction cups. One or two passages are often installed in the floor pointing upwards, one of which is used to supply CO 2 and the possible second, provided with a short hose and a stopcock, is used as a so-called false gas vent to remove the air in the shell, which is lighter as CO 2 to escape upwards.
Mode of action
The CO 2 supplied from a fermentation vessel collects below the inverted bowl. The gas diffuses into the liquid at the contact surface of the resulting CO 2 bubble with the aquarium water . Different sized shells result in contact or diffusion areas of different sizes. In this way, the amount of CO 2 to be dissolved can be adapted to the size of the aquarium.
Size calculation:
| Base size: 100 liters | |
|---|---|
| Carbonate hardness | Contact area |
| in KH | in cm² |
| until 10 | 30th |
| 11 | 50 |
| 12 | 70 |
| 13 | 90 |
| 14th | 110 |
| 15th | 130 |
| 16 | 150 |
Advantages compared to conventional CO 2 dispensing devices
Known addition devices (or called reactors), such as flippers, diffusers or external reactors (for introducing the CO 2 into the water of the filter circuit) continuously dissolve the gas supplied in the water. This addition is regulated by controlling the CO 2 flow rate.
This is also not a problem with the known pressure cylinder systems , since the amount of gas can be set to a constant value by means of a valve . In the case of biologically generated CO 2 , however, the gas generation does not run uniformly; it depends on the temperature and also on the length of the fermentation process. In addition, if the CO 2 flow is throttled, there is a risk of the fermentation tank exploding, which is normally only made of a plastic bottle or a canister and is not suitable for high pressure. However, since the contact area between the CO 2 and the water in the Paffrath channel is always the same and more or less is reflected in the gas production only in the level of the bowl used, an even addition of the gas to the aquarium water is guaranteed. If more gas is supplied than the bowl can hold, it simply escapes as a bubble over the lower edge of the bowl.
Disadvantages compared to conventional CO 2 dispensing devices
Due to the required contact surface, it is difficult to hide a Paffrath gutter inside the aquarium. Attachment can also prove difficult due to the buoyancy of the gas-filled shell.