Oyster Shell in Net Bag 5kg Filter Media

Oyster Shells

Oyster shells have been used for years by Koi professionals to help with the pH of the water and to maintain optimal water conditions, and it is extensively used in Japan.

Since the oyster shells will generally raise the pH level in your water, they should only be used in cases of low pH.

For those that have never been to Japan, oyster shells are extensively used by the breeders in Japan; these soluble (soft) shells are used to stabilise the pH.

Oyster shells stabilise the pH / KH-value which prevents pH crash. If the KH value drops this starts to dissolve the shells until the correct balance is reached again. Nitrifying bacteria also grows on the oyster shell.