Reef Endurance GFO Media – 1.25lbs is a phosphate adsorption media for fresh and marine aquariums. It helps in filtering out phosphates from the water column, promoting better coral growth and preventing algae outbreaks. The media has a porous structure with a high surface area that binds phosphate, silicate, arsenic, and other water-staining compounds. Initial dosing is 1 tablespoon per 10 gallons, with a maintenance dose of 2 tablespoons per 10 gallons, and should be changed every 4-6 weeks based on phosphate levels rising.