Koi Pond Clay Ponds or Mud Ponds

Page Summary:  The perfect koi pond as seen from the Kois perspective is a murky water pond and not as we strive to achieve which is a pond where the pondwater is crystal clear in appearance. It might come as no surprise to learn then that koi are actually reared in what are known as mud ponds... large open ponds with a distinctly muddy colouration but which are rich in minerals or micro nutrients favoured by the koi. Koi breeding which takes place in these ponds (known as Mud Ponds) results in successful breeding and a micro environmemt whre tiny koi can flourish.


A clay pond, also known as a mud pond, is widely thought to be a key means to nurturing some of the finest variety of koi in the world. Even though our own koi live in ponds with crystal clear water clarity and very filtered water, the reality is that we keep them in this environment for our own advantage – so that we can take pleasure in seeing them and admiring their beauty.

The Niigata koi farmers, however, breed some of the healthiest and most colourful koi in mud ponds that are cut out of the earth. These ponds are naturally rich in minerals, while the water clarity remains cloudy as the koi scavenge in the muddy top layer. Far from being filtered, these ponds are in fact enriched with manure.

Fortunately, we can reach a compromise between the water clarity we desire and the optimum mineralised conditions of the Niigata clay ponds. It simply involves you adding a clay like montmorillonite to your pond on a regular basis.

What are Clays?

Clay particles are minuscule crystals which are bound together lightly in sheets that can stack together and slip over each other. This is what gives wet clay its smooth, slippery texture. A fresh deposit of clay is created through the weathering of other materials. Examples of this process include kaolinite clay, formed through the weathering of the hard mineral feldspar, and montmorillonite clay which is created through the weathering of volcanic ash.

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Of these two types of clay, montmorillonite clays can carry more ions on their surface due to the increased spacing between sheets. This essentially means that this type of clay will be more effective in providing minerals to your koi pond.

How do Clays Work?

Clay particles, which are negatively charged, attract positively charged ions, allowing ion exchange to take place in the pond water. The longer the clay particles remain in suspension, the longer ion exchange can take place. Once clay particles have noticeably settled on the bottom of your koi pond, they will no longer be as effective. Therefore, using ultra-fine clay is most advantageous even though it is more difficult to prepare, as the clay particles remain suspended for a longer period of time.

The benefits of adding remineralising clay such as montmorillonite are great. All of the aquatic life found in your pond will use up minerals, causing the mineral content to become depleted over time. The regular addition of a clay will assist in replenishing the mineral content of your pond water, and thus stabilise the pH as well.

When it comes to clays and buffers, you don’t have to be fearful that you may administer an overdose. In fact, your pond water and koi should reap the rewards of a very stable aquatic environment.


Dont stress over pond pH and Testing Koi Pond pH

Interpet Koi Pond Test Kit

I will make a few very important points here which should be taken very seriously by anyone contemplating measuring pH in a koi pond and then TAKING ACTION based upon the measured result from testing the koi ponds water. If you test do it reliably... Interpet lead this pond water testing field of the koi keeping hobby

  1. pH of koi pond water will vary depending on time of day measurement is taken and especially if plants are in the pond. This means if you take a pH at 9am it will not be the same as a pH taken at 6pm. This single piece of information therefore must never be the information relied upon to make fundamental decisions
  2. pH is notoriously difficult to measure even in a laboratory with sophisticated instruments let alone in a koipond or fish pond using a piece of litmus type paper or a vial with coloured scales on it.
  3. If you must measure pond pH and this is a great part of the hobby then take the pond pH at the same time every day and plot the result on a graph. So now what youre looking for is not a single pondwater result but rather a pH trend in the pond water that you can use to sensibly consider a pH strategy.
  4. Very high pH in a koi pond is a serious threat to the well being of koi when levels reach about 9.5 because at this pH level ammonia which is a natural metabolic product of the koi and its existence becomes extremely poisonous
  5. It would be extremely rare for a koi pond to reach dangerous pH levels but could well occur in koi ponds with serious algae problems

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Over-wintering koi goldfish hibernation cold freezing water ice

Koi pond heating using gas electric in UK temperature control

Should I heat my new koi pond this winter. What temperature?

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To Feed or not to feed your pond fish or koi or goldfish

How Do I care For My Garden Fish Pond In Cold Winter

Frozen Koi Ponds & Fish Ponds. Ponds Freeze in Winter. Pond Care in Freezing Winter Weather

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