Alka-Buffer, also referred to as carbonate hardness or buffering capacity, is essentially a means of quantifying the stability of pH in a solution, such as aquarium water. Alkalinity is of extreme importance in a marine aquarium, owing to the manner in which it influences pH. In an aquarium, weak acids formed by oxygen respiration and the decomposition of organic material gradually deplete alkalinity. If left unchecked, the alkalinity drops below a critical level and pH begins to fluctuate more wildly than is normally suggested (a daily pH shift of +/-0.2 is normal in marine aquaria), causing stress to livestock. Alkalinity is also depleted by reef-building organisms during the production of aragonite (~60% carbonates by weight), and is therefore very important for their rapid growth.