Nothing spoils the appearance of an aquarium more than algae. Although there are a number of other things can help to reduce algae growth. Although not a replacement for proper tank maintainence, sometimes your aquarium just needs a helping hand and that's where API Prevent Algae comes in! Excessive algae growth usually results from an excess of nutrients in the water which the algae then thrives on. API prevent algae consumes some of the excess nutrients in the water reducing the amount available and as a result effectively curbing algae growth.