Bentonite, also known as montmorillonite clay or Koi clay, is used in Koi ponds for various reasons. It is available for Koi ponds in powder form. Bentonite has coagulating properties, so it will absorb any fine particles that are suspended in the water and it will settle on the bottom of a pond or a filter.
Adding bentonite to a Koi pond is also beneficial to a Koi’s immune system, for it has many good minerals in it. Koi get all of their nutrients either from the food they eat or from the water directly. Bentonite can even be added to Koi food to make it have a greater mineral content.
Koi clay (bentonite) can also be used to remove string algae from a stream. Take some of the clay, spread it over where the string algae is growing and it will detach it from the stream bed.
Bentonite is also used as a liner for mud ponds. It is moved in the pond hole with a bulldozer and then tamped until it is about a foot thick so that it forms a waterproof layer.
Bentonite is a rock that is made of claylike minerals. The most common clay minerals in bentonite are members of the smectite group (mostly montmorillonite); other components of bentonite include biotite, feldspars, illite, kaolinite, quartz, and volcanic glass. There are two types of bentonite: swelling bentonite, which is also called sodium or western bentonite, and non-swelling bentonite, which is also called calcium, or southern, bentonite. Both types formed through the alteration of volcanic ash that was deposited in a marine environment. Bentonite is mined mainly in the Western United States and Greece. Most of the bentonite mined in the United States is used in oil and gas well drilling.
The term clay refers to a number of earthy materials that are composed of minerals rich in alumina, silica and water. Clay is not a single mineral, but a number of minerals. When most clays are wet, they become "plastic" meaning they can be formed and molded into shapes. When they are "fired" (exposed to very high temperatures), the water is driven off and they become as hard as stone. Clay is easily found all over the world. As a result, nearly all civilizations have used some form of clay for everything from bricks to pottery to tablets for recording business transactions.
The minerals that make up clay are so fine that until the invention of X-ray diffraction analysis, these minerals were not specifically known. Under extremely high magnification, one can see that clay minerals can be shaped like flakes, fibers, and even hollow tubes. Clays can also contain other materials such as iron oxide (rust), silica, and rock fragments. These impurities can change the characteristics of the clay. For example, iron oxide colors clay red. The presence of silica increases the plasticity of the clay (that is, makes it easier to mold and form into shapes).
Koi clay (bentonite) can be found in a variety of places. The best place to get Koi clay (bentonite) is from a good bulk supplier. One hundred pound bags of the stuff can be bought very cheaply. Watch out for unscrupulous dealers, they will sell bentonite at a very inflated price and will tell you that there’s “special” ingredients in it to justify the high price. Bentonite is just clay from the earth, it has no secret ingredients or special additives.
Back to Koi Care.