Advantages of a biofilm reactor for water treatment

• An active biological system in the biofilmreactor for water treatment of ponds right from the start.

 • Nitrification and denitrification in the biofilmreactor as in a natural nitrogen cycle; removal of nitrite and ammonium/ammonia.

 • Reduction of microbial density (number of microorganisms) in free water, muddy water clears up.

 • Removal of essential nutrients (nitrogen, phosphate) of algae, which results in the reduction/prevention of algae growth.

 • The biofilm in the biofilmreactor will weather most drug treatments well.

 • Extremely space-saving and combinable with other system, especially if their performance is too low.

 • Available in gravity-driven and pumping versions.

 • No problems in cold winters, the fastest initiation in spring without any “starting bacteria”.

 • No more expensive cleaning operations, thus only low-maintenance is required.

 • Microorganisms in the biofilm will survive the harshest conditions over a long period of time.

A biofilmreactor after two years of use

These pictures show the interior of a biofilmreactor which, as the sole biological water treatment system, has continuously been providing very good water values in a koi pond for two years. The koi pond has a volume of 21 m3 and contains about 22 koi (40-65 cm each) and 2 sturgeons.

In the last two years, the biofilmreactor has been operating nonstop, which is what we also recommend. The fish survived the winter very well. In spring, the biological system was, as expected, in less than two weeks fully active again.

Initially, the biofilmreactor was mounted to an upstream sieve filter cartridge as a mechanical preliminary stage. The water values were good also at this time. However, a much more efficient upstream drum filter has been used as a mechanical preliminary stage for about a year now.

Bild: Die PE-Einheiten des Biofilmreaktors nach zwei Jahren Laufzeit - der Biofilm ist schön auf den Höhen und in den Täler der PE-Einheiten sukzessive aus dem soliden Biofilm gewachsen. In dieser Konfiguration kann der Biofilm all seine positiven Eigenschaften voll entfalten.

Photo: PE units of the biofilmreactor after two years of operation: The biofilm on the higher and lower surfaces of the PE units has gradually grown well from the solid biofilm. In this configuration, the biofilm can fully develop its positive properties.

The interior of the tubes is unobstructed. A flow of the pond water that corresponds to the water volume (about 10m3/h), behind the drum filter, is fully guaranteed even after two years. An interim “cleaning” of the biofilmreactor did not take place and was, as expected, not necessary.

The biofilm filters the “dirty” components (e.g. organic carbon, nitrogen, phosphate etc.) from the water, which is typical for the biofilmreactor compared to other biological pond filters.


With the removal of nitrogen compounds from the water, both the nitrification and denitrification will be achieved in the robust biofilm by the microorganisms that have been previously developed right from the start.  This is reflected in the values of ammonium, nitrite and nitrate. With an activity of the biofilm like that, the number of water changes is significantly reduced, that is, 50%.

Positive results

The illustrations above clearly demonstrate that the biofilmreactor will not, even after a long-tem operation, develop excessive bio mass, as in the case of traditional filter systems. This result was also expected since it reflects a typical feature of biofilms.