Use 250 mL for every 150-225 L (40-60 US gallons). For best results, SeaGel should be placed to maximize water flow through it. Use in a filter bag, such as Seachem's Zach Bag. Rinse with fresh water before use. Be cautious, as the product may spray and warm up during initial wetting. SeaGel will perform for 3-4 months.