Why use oyster shells in a pond or basin?

There has surely been a time when you noticed oyster shells in certain ponds. Regardless of the aesthetic appeal they provide, these shells play an active role in the pond's ecosystem. And for good reason: they are excellent factors for stabilizing the carbonate hardness (KH) and the total hardness (GH) of the water.

People tend to think that if the tap water they use is harder, it shouldn’t pose any problems for the water's KH and pH. Since KH acts somewhat like a buffer for the acidity of the water (pH), it is always a good idea to test the water parameters before drawing any conclusions.

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Carbonate hardness (KH): an important but often overlooked value

Fish, plants, and the biological filter "consume" water hardness (KH). If the water is not changed enough during the winter, for example, the KH can drop rapidly. This also happens during rainy periods. By extension, this type of variation can have major consequences for the fish. Indeed, in these situations, the pond's pH can drop suddenly.

KH is not measured regularly enough in ponds. Only in the event of problems—and therefore when it is already too late—do people try to remedy the situation by adding, for example, KH+ powder. However, this powder has a number of disadvantages:

• a lot of powder disappears into your filtration system (backwash)
• an effect that is only boosted in the short term
• large fluctuations in water values
• if it rains, you have to add more KH+
• you have to constantly measure and add powder

How to stabilize the pond's GH and KH hardness?

In detail, it is quite easy to regulate the total and partial hardness of the water. Depending on the situation, you can choose to use products or turn to other alternatives. In this case, to stabilize the pond's GH and KH, you can use Optiminera or apply a more natural solution like oyster shells.

Optiminera: the minerals offered by Aquatic Science

Optiminera products are suitable for those who want to clear the water, accelerate the reduction of sludge, or lower phosphate levels. These are natural minerals, perfectly adapted to optimize pH and hardness over the long term.

In parallel, as it contributes to the stabilization of the pond, Optiminera also helps in the prevention of diseases. In practice, Optiminera minerals should be spread over the surface of the pond. You should focus particularly on areas where there is good water circulation.

There are super practical packs like the Ichi Pond Starter Kit, which allow you to have the necessary items close at hand. In other words, this starter kit includes:

• food for Koi carp
• Optiminera
• Optinit
• the Biobooster
• Bactogen

Oyster shells: a natural, long-term solution

Beyond their culinary value, oysters can still play a major role in the pond. Specifically, we are talking about oyster shells, which are capable of ensuring the regulation of a pond's KH and pH. In detail, these shells dissolve only when the KH value drops. At that point, they act as a buffer for the pH (the acidity level of the water).

They do not depend at all on the amount of rain, water changes, or the seasons: oyster shells ensure a stable level of the water's KH and pH values. However, once the oyster shells are practically dissolved, it is necessary to add more.

For information: one bag of oyster shells per year for a volume of 10 m3 will suffice. Of course, the necessary quantity naturally depends on the factors described above.

Oyster shells are generally used in water that is too soft, in order to increase the carbonate hardness. In parallel, the shells are also suitable to serve as biological filtering material. They can therefore be installed in a drip system or in a multi-chamber system.

The oyster shells offered on FouDeBassin.com are washed with chlorine and then dried. This is a guarantee that harmful bacteria, fungi, and other germs are well eliminated. Finally, the oysters are delivered in a net, which can easily be rinsed if necessary.

The advantages and disadvantages of soft water

Soft water is not absolutely good or bad. It will depend primarily on how you intend to use it. Obviously, water hardness will have an impact on the ecosystem: fish as well as vegetation will develop differently.

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What are the advantages of soft water?

• Promotes the growth and development of the red coloring of Koi carp
• Limits the accumulation of ammonia.

What are the disadvantages of soft water?

• For Koi carp: a less clear white complexion and black that evolves less well.
• The fish's osmoregulation must be more efficient
• Promotes the development of unwanted algae.

How to increase carbonate hardness?

• Adding harder water.
• Adding limestone, in the form of stones or shells