Fauna Marin Ultra Carb 2500 ml Ultra-Carb L is an acitvated carbon specifically made for permanent and long-term use. Extremely pure, vapor-activated and pre-washed activated carbon for efficient removal of yellowness, turbidity and harmful toxins, essential for maintaining good water quality in any aquarium. Ultracarb is almost entirely free of phosphate and has an extremely high capacity. Ultracarb is specifically made for permanent and long-term use but should be exchanged every 30 days. Suitable for freshwater and marine aquaria, cleans the water without any negative side effects.