Koi pond

The Biofilmreactor in koi ponds

The external design of the biofilmreactor is extremely variable. It can be used, for example, with drum filters, fleece filters or other effective preseparation systems. Key is – and this applies to all biological systems – that filtrations of dissolved substances should be about 100 µm - lower levels about 40 µm are even better. Otherwise, the active biological system is covered and the contact with the water which is to be purified will be insufficient.

First it must be considered whether the biological plane, i.e. the biofilmreactor, is activated by a pump or driven by gravity. If the biofilm reactor is activated by pump, the case is made from polyethylene (PE). This case is pressure-tight and can resist the necessary inflow or ram pressure. Prior to the sealing of the PE case, the carrier surfaces for the biofilm will be implemented within the case. The carriers, so-called immobilization units (IU), are made of PE and provide an appropriate growth area for the biofilm.

The actual active part of the biofilmreactor is the inner workings along with the immobilization units of PE on which the solid biofilm is created in advance. The biofilm is active immediately after its installation in the pond water cycle.

Unlike traditional systems, it takes no time at all for the biofilm reactor to develop a biofilm by the flow of the pond water.

The sound biofilm of the biofilmreactor is developed and created by a process of environmental technology on the immobilization units within 4 to 7 days. In the process, only microorganisms are used that are present in the pond for which the biofilm reactor will be built. No genetically manipulated or foreign species of microorganisms are used which are not able to withstand the so-called wild type in the pond in the long term anyway.


The photo shows the interior of a biofilmreactor made of KG2000 (PP = polypropylene) tube.

Photo gallery

Below are listed some biofilm reactors which have been developed and installed for different systems and applications. For information about your own application, please send us aNachricht  (message)   or contact the distributors of the biofilm reactor.

Koipond new plant

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New construction of a 50 cbm koi pond in Ahaus. In the foreground the chamber with a drummer and afterwards the biofilm reciter - with 4x1 m d250 KG2000 pipe. Then comes the pond heating in the IBC container.

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The complete plant with approx. 50 cbm. The water quality is excellent - the only biology is the biofilm reactor with a surface area of approx. 11000 sqm - which was covered in advance with an adapted biofilm. This biofilter corresponds, converted to Helix/Kaldnes, to a filling quantity of approx. 14 cbm! Furthermore, when using Helix/Kaldnes, a biology has to build up first and this can take some time.

Koi pond restoration

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Koteich with approx. 30 cbm, as water treatment served a drum filter and as biological stage so-called Lavarock.

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This constellation was very unfortunate, because already after some time the lava rock filter was completely rotten - in the truest sense of the word. As a result, the water values became very poor and all koi died. The customer asked us for help and we were able to help him to find the desired pond and water quality.

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The original biological filter of the Koiteches - Lavarock - was completely removed and the chamber cleaned. The pictures speak for themselves - as far as the quality of the Lavarock filter is concerned.

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The drum filter was overhauled and had to be redirected because it was installed too high. This of course meant that the gravitational current was too low.

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The lava rock filter was completely removed and a biofilm reactor - with 4x1 m d200 and a surface of approx. 6400 sqm delivered with biofilm - was installed. This provided the necessary good water values and fish are already swimming in the pond again.

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The customer is finally satisfied with his koi pond. This example shows the absolute necessity of using appropriate filter systems for water treatment - especially for the koi pond. Wrong systems quickly show their disadvantages - to the disadvantage of the customer and the Koi, of course.

Koi dealer Nederkoi NL


Nederkoi in Leunen (Holland) - Koi trade and rearing - Ton Hermans, our dealer in Holland

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The two illustrations above show the Nederkoi demonstration basins. Cartridge filters used to be connected here. Ton Hermans has switched over to the biological purification of the water with the biofilm reactor. A drum filter serves as a mechanical preliminary stage. The water values are excellent.


Biofilmreactor - 5x1 meter, d200  with inlays, surface over 7500 qum - for large tanks with 20 cbm each

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The breeding basins at Nederkoi, 4x 20 cbm each, are all equipped with a biofim reactor as a biological filter - this has been the case for five years. The water quality is excellent and the Koi thank us with special quality and lowest mortality.

A detailed test was carried out in these basins. Two basins were occupied with approx. 200 Koi of the same age. One basin had the biofilm reactor as a biological stage - the other had the conventional system. Both systems ran for about 6 months.

Koiteich Biofilter Koiteich Biofilter

Photos: Biofilmreactor, PE tube ( 4 x 160 mm Ø  ) welded, flange connection; to be seen at Vitus Zoo Pond, Kaiserslautern, for the retailer’s koi pond (approx. 20 m3).


Biofilmreactor (green, KG2000, Ø 225 mm), 6 x 1 m, behind a drum filter, for a koi pond, approx. 45 m3, with  more than 120 kg live weight of koi; Koicrew Europe, Krefeld.


Koiteich Biofilter

Biofilmreactor installed behind a chamber filter, 4 m of KG2000 tube (Ø 200 mm), return flow to the pond, approx. 40 m3; to be seen at Koi Fischer, Lindlar-Kapellensüng.

Koiteich Biofilter


Photos: Biofimreactor made of KG2000 tube, behind a drum filter, for a koi breeding pool of about 20 m3 (see photo below), size approx. 3 x 1 m, tube Ø 200 mm; to be seen at Meckoi, Meckenheim, installed in 2007.

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Koiteich Biofilter

Biofilmreactor made of PE tube (Ø 200 mm), welded, behind a drum filter in the filter trench for a koi pond of about 24 m3 containing 15 koi; family N., Cologne, installed in April 2008.



Biofilmreactor in a former planting bed which is now obsolete and filled up, a nonwoven filter serves as a precursor, koi pond about 20 m3, size approx. 3 x 1 m, KG2000 tube (Ø 160 mm) plus connecting piece; family Gerhard B., Kamen, installed in 2007.



Photos: Biofilmreactor, 5,5 x 1 m, KG2000, (PP, green), Ø 200 mm; koi pond is about 70 m3, drum filter and Cheops filter as mechanical precursors; Odenthal, installed in April 2011.



Photos: Biofilmreactor, 4 x 1 m (Ø 225 mm), welded PE, beneath a drum filter, flowed by gravity, for a koi pond, approx. 100 m3, flow approx. 80 m3/h; to be seen at Koi Palast, Bünde, installation in May 2011.


Koiteich Biofilter 

Photos: Left – appropriate biofilmreactor, installed behind a chamber filter for a koi pond of approx. 16 m3 containing 25 koi, size approx. 4 x 0.8 m, PE tube (Ø 160 mm); right: screwed connection for PVC; family Michael H., Kürten, installed in April 2009.

Koiteich Biofilter

Koiteich Biofilter 

Photos: Biofilmreactor in a filter trench, installed beneath a drum filter, koi pond of 50 m3 containing about 50 koi, size 3 x 1 m, Ø 225 mm PE tube; Solingen.

Koiteich Biofilter


Photos: Biofilmreactor (green tube of KG2000), 3x1 meter, Ø 200, behind a chamber filter for a koi pond of approx. 65 m3; family Henry M, Monheim, installed in July 2010.


Koiteich Biofilter

Photos: Biofilmreactor installed behind a paper-woven fleece filter, for a koi pond of about 8 m3 containing 25 koi! Size is 4 x 1 m plus PE attachment, Ø 250 mm; Wuppertal.

Koiteich Biofilter

Koiteich Biofilter

Photos: Biofilmreactor for a koi pond of 120 m3 containing about 70 koi with a preceding drum filter, size of the biofilm reactor is 70 (L) x 70 (W) x 160 (H) cm, PE tube (Ø 250 mm) with attachments;  Kaiserslautern, installed in December 2008.

Koiteich Biofilter


Photos: Biofilmreactor for koi pond, KG 2000 tube, Ø 4 x 160 mm, pond volume 40 m3, installed behind a drum filter; Landsberg, installed in April 2011.


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Photos: Biofilmreactor (2 x 2 m, KG 2000 tube) for a koi pond of about 40 m3, containing approximately 20 koi; behind a drum filter; Springe, installed in May 2011.

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