Aqua Vitro Phosfiltrum

Aqua Vitro Phosfiltrum is a specially formulated, high-density, granular ferric oxide (GFO) product. It will quickly remove phosphates and silicates from both freshwater and saltwater aquariums and prevents their return. It does not break down into fine particles.
Instructions for use:

Rinse before use.

Use 50 g (¼ cup) for every 300 L of saltwater or 600 L of freshwater.

Leave the product in place for 4 days, then test the phosphate or silicate concentration in the aquarium water.