EBayRemoves nitrates, nitrites, ammonia, and organics High porosity biological media Pore size well suited for anaerobic bacteria No danger of hydrogen sulfide production as with sulfur based media De Nitrate helps to remove the Nitrates, Nitrites, Ammonia and organics from your aquarium. De Nitrate is a very economical, natural, porous material with a geometry that promotes aerobic nitrification on the first few mm of depth and then anaerobic denitrification at the core ( low oxygen level bacteria, this allows the bacteria to consume the nitrate out of the water column which aids nitrate reduction - must be used at under 200 litres per hour ). Aerobic bacteria grows in water flow over 200 litres per hour, anaerobic grows in water flow under 200 litres per hour. If you are wanting to reduce nitrates and ammonia in an aquarium with a flow rate of >200l/hour please use  Matrix De Nitrate has a really high surface area which allows bacteria to grow in a low oxygen level of water. This aids in the reduction of the nitrate within your aquarium. De Nitrate is best used in a low flow area of your aquarium, either within the filter box of an external filter,a seperate media reactor or an internal filter that has a flow of under 200 litres per hour 500ml of De Nitrates 100-200L of water