Oyster Shell

The complete shell assures you, that you buy 100% Oyster Shell, which is 95% Calcium carbonate. Japanese Koi Breeders have been using Oyster Shell for generations to maintain a stable pH, they use Oyster Shell as their only pH buffering media.

The soft soluble shells slowly dissolving when the water starts losing pH and becoming Acidic. When Oyster Shell’s dissolve it releases Calcium Carbonat which pushes KH higher which then buffers the pH.

Oyster Shells are the best for maintaining KH and thus buffering pH. With Oyster Shell you will never need to worry about your pH crashing.