Edging stones or gravel are not strictly required for a koi pond, but they serve several useful purposes that can improve both function and appearance. Edging stones help define the boundary of the pond and prevent surrounding soil from eroding into the water, especially during heavy rain. They also provide a finished, natural look and can help conceal the pond liner for a more seamless design.
Gravel, when used on the bottom of the pond or around the perimeter, can enhance the aesthetic and create a more natural habitat for beneficial bacteria, which contribute to the pond’s biological filtration. However, too much gravel inside the pond can trap debris and make cleaning more difficult, so it's best used sparingly or in specific areas. Both edging stones and gravel can help stabilize the pond’s edge and make it safer by reducing the risk of slipping.
