Add 1-2 leaves per 20 liters (5 US gallons). Remove and replace every month or as desired. Catappa leaves may float initially but will sink after 2 - 3 days. To make an extract, boil three grams (approx. two-and-a-half leaves) in 1 liter (1 US quart) of water for ten minutes or until desired color is attained. Let extract cool to aquarium temperature and pour directly into the tank or mix with prepared water for water changes. When first using extract, add gradually over a 2 to 3 days and monitor to ensure pH stays within suitable range for tank inhabitants. Chemical filtration media such as activated carbon can remove compounds provided by Catappa leaves.