The pH of natural seawater is remarkably stable due to its nearly inexhaustible stock of dissolved buffers (mainly bicarbonates), which prevent pH changes. In an aquarium the buffering substances are used up by calcareous algae and invertebrates and by the acid waste products of the fish.  A low buffer capacity (alkalinity) may allow a sudden fall in pH which would be very dangerous to all organisms in the aquarium. Marine Success Buff contains carbonates and bicarbonates of Sodium, Potassium, Calcium, Magnesium and Boron blended in the ratio as found in natural seawater.  When used weekly as directed, Buff will maintain a high buffer capacity and a stable pH.