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 bagNow with ferric oxide to remove phosphates and silicatesFor freshwater, marine and reef aquariumsChemi-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.