Dosage : New Aquariums : Day 1: 25 mL per 38 L (10 U.S. gal) Day 2: 10 mL per 38 L (10 U.S. gal) Day 3: 10 mL per 38 L (10 U.S. gal) All regular maintenance activities (water changes, filter maintenance, etc.) : 5 mL per 38 L (10 U.S. gal) After adding new fish and/or medicating : 10 mL per 38 L (10 U.S. gal) Weekly dosage to maintain a strong beneficial biological colony : 5 mL per 38 L (10 U.S. gal) Treats : 3,785 L (1,000 U.S. gal)