Check the listing for details. SEACHEM de*nitrate Reducer Anaerobic Aquarium Filter Media denitrate. Condition: New. Listed at 14.18 USD. SEACHEM de*nitrate™ Auction is for ( 1 ) : SEACHEM de*nitrate™ Removes nitrates, nitrites, ammonia, and organicsHigh porosity biological mediaPore size well suited for anaerobic bacteriaNo danger of hydrogen sulfide production as with sulfur based media Description:de*nitrate™ is an economical, natural, porous material with a pore distribution and geometry that promotes both aerobic nitrification within the first few millimeters of depth and anaerobic denitrification at the core. The material has a high surface area and supports a high density of bacteria. Although de*nitrate™ has capacity to trap nitrate, this, as with other nitrate retaining materials, such as certain zeolites and synthetic resins, is quite limited and the primary mechanism of nitrate removal is anaerobic.“Live” rocks or reef rocks remove nitrate by anaerobic denitrification. de*nitrate™ removes nitrate by the same process. Efficiency is magnified several folds by forcing the water to filter through the porous de*nitrate™. As with reef rock, anaerobic conditions are achieved by the porosity and the depletion of oxygen by the aerobic process at the surface. Excessive flow rates should, therefore, be avoided, as they may impede development of an adequate anaerobic environment to support denitrifying bacteria. de*nitrate™ is also an excellent media for aerobic nitrification and it makes an ideal biological filter in drip trays, canister filters, sumps, or even box filters. At high flow rates (greater than 100 US gallons per hour), it will function solely as an aerobic filter. At slow flow rates (less than 50 US gallons per hour), it will function as both an aerobic filter and an anaerobic denitrifying filter. Please feel free to contact me for International and combined auction shipping rates or with any questions or concerns that you may have about my product. Thank you !