Shake well before use. Turn off UV/ozone. Use 1 capful (5mL) for each 40L (10 US gallons) on the first day with a new aquarium. Then use 1 capful for each 80L (20 US gallons) daily for 7 days. Fish and other aquatic species may be introduced at any time as long as dosage is maintained for 7 days. For optimum biofilter performance use 1 capful for each 80L (20 US gallons) once a month or with each water change and whenever introducing new fish or whenever medicating an aquarium..