Koi Fish Ponds

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How to Remove Odour From Koi Ponds

How to Remove Odour From Koi Ponds

One of the worst nightmares of koi pond owners is to remove unpleasant odour from their koi pond. A well-designed pond reduces the chances of pond odour.


What is the common cause of Koi Pond Odour?
Accumulation of Sludge is the common cause of unpleasant odours in Koi ponds.

In most of the cases, the odour is by the sludge, biological wastes which accumulate over time. There are different types of waste which contribute to the formation of sludge. Excreta of fish and other aquatic living things.

  • Food waste

  • Dead leaves

  • Dead surface algae.

  • Type of koi food

The above are some examples of elements which contribute to the formation of sludge in koi pond over some time.

The koi pond is a closed-loop ecosystem which is if designed correctly will be able to control the pond odour. 

The best option is to have a biofiltration chamber with an ample supply of oxygen. The beneficiary bacteria will help clean up the sludge and the dissolved ammonia and harmful chemicals. There should be provisions in the biofilter chamber to remove the bottom sludge periodically.

Dissolved Oxygen

Dissolved Oxygen content is another factor which affects the pond odour levels.

Oxygen enters the water naturally when it comes in contact with the water or as a waste product of photosynthesis from phytoplankton, algae, seaweed and other aquatic plants.

During designing a fish pond it is wise to include a waterfall or a water feature to your pond which will help mix oxygen to the pond water.

A fountain or a waterfall will help to agitate the water and will provide additional circulation and diffuse oxygen into the pond water. Remember that a water feature is not a substitute for aerators and diffusers. The depth of the pond plays a vital role in maintaining high oxygen levels in the water.

Shallow ponds water heats up quickly and less oxygen it can hold. The actual amount of DO (dissolved oxygen) in mg/L will change depending on temperature, pressure and salinity.


Denitrification is the process of removing nitrogen and phosphorous from the pond water using a specific blend of bacterias. Nitrate is one of the key growth factors of algae. Algae and other vegetations absorb nitrate and other nutrients from the water to grow.

This is achieved using specially blend bacteria which are induced to the pond at specific intervals. These genetically engineered bacterias feed only on nitrates and phosphates present in the water.

There are genetically gendered and non genetically engineered bacteria available in the market for this application.

If you’re interested in a customized blend of bacteria for your pond, that comes in easy to use packs, saves water and electricity, prolonged cleaning cycle of your filters and is eco-friendly kindly get in touch with us.

Sometimes a full and thorough cleaning of the pond is necessary. When there are too much sludge and debris such as dead leaves, twigs, etc, in the bottom.

The first step is to move out the fish to a well-aerated portable holding tank or similar setup. Once the fishes are transferred to the holding tank start pumping out the pond water.

Thoroughly clean and vacuum the pond bottom and sides, if necessary use a high-pressure cleaner. Allow it to sun dry for a day or two. Or disinfect the pond using suitable means and methods.

Remember to Check, clean and upgrade the current filter system

Refill the pond with the source water, during filling start the aerators and water features if any. It will help in bringing up the dissolved oxygen levels in the pond water much faster.

Before shifting the fishes back to the clean pond, cycle the pond water and add necessary beneficial bacterias to the biofilter. This thorough cleaning process will help sort out unpleasant odours from the pond.

Addition of UV Water clarifier
Uv water clarifier helps in controlling the single-celled alga growth thereby giving water clarity. Low algae growth also decreases the biological load in the pond.

As water is the source of all life forms water quality is of very much important for the survival of Koi fishes. The routine cleaning of filters and the mandatory water tests shall be done periodically so that abnormalities in the water parameters can be identified at an earlier stage.

If you need help with solving pond related problems or designing pond and filters kindly get in touch with us.

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KJA & Sons - Engineers and Contractors
CC – 15/ 68 A, West Karuvelipady, 
Kochi – 682005

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