Does a protein skimmer make sense for freshwater?
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In a protein skimmer, proteins accumulate on the surface of the air bubbles. The egg whites can then be removed with the foam. They are thus removed from the water before nitrification can mineralize them. Protein skimmers are often also called skimmers.
The bubbles must be as small as possible so that enough protein molecules can accumulate on the surface of the air bubbles. They also have to rise to the surface of the water as slowly as possible.
The rate of climb is influenced by the salinity of the water. The higher the salt content, the slower the bubbles rise.
Protein skimmers only work effectively with salt concentrations from brackish water onwards.
Skimming performance is very low in fresh water. Stable bubbles do not form there due to the low density or due to the high surface tension of the fresh water from protein and air.
In the case of freshwater skimmers for sale that have a tube with Siporax inside, the filter effect of the Siporax has a significantly greater effect in normally loaded aquariums than pure skimming. The skimmer basically only increases the filter surface. This can be achieved more easily with a large, throttled filter.
Freshwater skimmers are sometimes recommended to remove scum. A surface skimmer is more suitable for removing scum. As a rule, however, the scum disappears as soon as the pollution of the water is reduced.
A skimmer has a similar effect on CO2 as an oxygen stone. In both cases small air bubbles are generated. Because the water surface is not moved with a skimmer, the CO2 discharge is probably lower.
A skimmer also removes bioactive organics that act as chelators, protect mucous membranes, or act as a disinfectant. Vitamins are also skimmed off.
The risk of disease may increase significantly.
Humic substances are predominantly colloidal. Colloids are preferably skimmed off.
Trace elements adsorbed on the colloids are also skimmed off. This includes at least part of the iron. These trace elements are then missing from the plants, whose growth conditions are thus deteriorated.
The higher the pollution of the aquarium water, the sooner a skimming effect can be seen. Because the foam in fresh water is not as stable as in sea water, a slightly thinner broth runs into the foam cup.
This causes a significant loss of water. The aquarium has to be refilled practically every day. A test of a skimmer confirmed that water was consumed.
Experiences with a skimmer in an aquarium for rays confirm the high water consumption. The device was able to remove protein, humic substances and other surface-active substances from the aquarium, but did not come close to seawater skimmers in terms of performance. Despite the special design of the freshwater skimmer with tubes that are supposed to stabilize the bubbles, the skimmed concentrate was not nearly as concentrated as in the seawater skimmer. But the volume was significantly higher and amounted to 5 – 10 liters per day.
Another problem was the tuning of the skimmer. Because the water level is constantly reduced by the skimmed concentrate, at some point nothing comes out. If the water cannot run straight down a drain, there is a risk of water leaking out before the right settings are found.
A skimmer makes no sense in densely planted and normally stocked aquariums.
A skimmer was tested in a 500 liter aquarium for 24 days in the magazine Aquaristik aktuell Issue 9 – 10/99 p. 38, 39. The aquarium was stocked with South American cichlids, tetras and catfish. The conditions in the two aquariums were the same. A skimmer was used in one aquarium, the other aquarium did not have a skimmer. In the aquarium without a skimmer, the same amount of water was changed as was added in the aquarium with a skimmer due to the skimmed concentrate. The nitrate increase decreased by 30% from 25 mg/l at the beginning to 70 mg/l instead of 100 mg/l after 24 days. The phosphate value remained constant at 2 mg/l with the skimmer. Without a skimmer, the phosphate value rose to 4 mg/l.
A skimmer can be useful in heavily loaded tanks, e.g. B. Breeding facilities, fattening farms, husbandry facilities for edible fish and possibly for zoological activities. An automatic water inlet and outlet into the sewage system should be available. The water flow can then be greatly reduced because more pollutants are removed with the concentrate. In addition, the water is intensively aerated.