Boyd Chemi Pure Elite features the same powerful filtration media as original Chemi Pure but with added ferric oxide to remove phosphates silicates and red slime cyano bacteria for cleaner clearer water. It also supports aerobic bacteria growth and removes dissolved organics in all aquarium types. Superior filter media in durable nylon bag Now with ferric oxide to remove phosphates and silicates For freshwater marine and reef aquariums Chemi Pure Elites unique formulation enhances aquarium health and supports longer fish life. It helps eliminate foul odors removes toxic elements such as copper and phenol has a safe pH range reduces water changes and causes no osmotic shock or ion antagonism. It increases appetites of all fish species with no acclimation time supporting healthy metabolism. Directions Use 1 Full Unit for 40 gallons 2 Full Units for 40 100 gallons and 1 extra Full Unit for every additional 25 gallons. Replace bags every 4 6 months for maximum effectiveness.