What is Alkalinity, and Why Is It Important?
Alkalinity is the acid-neutralizing capacity of water, and is due to the presence of carbonates, bicarbonates, hydroxides as well as other bases including borates, silicates, phosphates and others. We are most interested in the bicarbonate content of reef water since it not only buffers against modulations in pH, but acts as a major inorganic carbon source for zooxanthellae photosynthesis (carbon dioxide being another source). Alkalinity is destroyed during the conversion of toxic ammonia to relatively harmless nitrate. Calcium carbonate (in the form of aragonite) constitutes a major portion of coral ‘skeletons’. In short, alkalinity is one of the most critical parameters to monitor and maintain. (Note: It is not the intent of this article to extensively discuss alkalinity and any of the many caveats in its proper determination and sources of potential error. These have been the fodder for more than a few articles. For example, see Randy Holmes-Farley’s in-depth comments at www.advance
