High performance activated carbon for crystal clear water in freshwater and saltwater aquariums.Rowa Carbon is a high grade granulated carbon with an extremely low phosphate content.RC 501 – 500mls. * Includes media bagRowa Carbon is an unusually high-performance activated carbon based on the finest quality hard coal and contains extremely low levels of Phosphate.Within the aquarium activated carbon will remove toxins and yellowing from the water which will improve the health of your livestock and improve the penetration of light leaving your aquarium crystal clear.Many low cost carbon products on the market place are washed in phosphoric acid as a final stage of their preparation and can release high levels of Phosphate into the water. Rowa Carbon Contains extremely low levels of Phosphate.Problems with algae are often caused by the release of phosphate from activated carbon with high POI (Phosphate Output Index) levels – often as high as 14.0, which inhibits lime synthesis in coralline algae, corals and other organisms that deposit lime.Rowa Carbon is distinguished by its exceptionally low POI level of only 1.3 which is considerably below detection levels of phosphate test kits available to the hobbyist.Features: