Nutrafin Clear Fast - Particulate Water Clarifier is a fast-acting particulate water clarifier that will clear green water in 1 to 3 hours. Clear Fast creates ionic attraction between minute suspended floating particles, such as algae, dirt, silt, and fine sand, clumping them together into larger particles for easy removal by the aquarium filter. Use Clear Fast to clarify cloudy aquarium water resulting from tank disturbances, floating debris, aquarium maintenance, new gravel introduction, and suspended algae (green water). For best results use with a filter equipped with polyester media. For freshwater use only. Size: 120 mL (4 fl oz) DOSAGE: Dose at 2.5 mL per 38 L (10 U.S. gal) * DO NOT OVERDOSE. Water clarification is usually visible within the first 3 hours. If the water remains cloudy after 24 hours, repeat the initial dosage. Ensure good filtration. For optimum results place polyester filter wool or pad in the filter and remove it when the water has cleared. Treats: 1,824 L (480 U.S. gal)