Aqua Medic Denigran is a type of granular media made of special plastic material to enhance the settlement of nitrate removing bacteria. The main nutrient, nitrate is removed from the algae without any chemical additives, additional feeding of the bacteria is not required. The optimal designed mesh bag gives the best possible water flow past the media. Depending on the population, Denigran will be effective for up to 12 months.Thats why the nitrate content should be reduced Nitrate is produced in most aquaria from livestock feeding and dead plant matter, in larger quantities than it is consumed by the existing plants. One way to reduce the nitrate content is to change the water regularly or to use nitrate filters. In case the tap water has already higher nitrate content and the water desalination or controlling the nitrate filter is too complex, you can use the Aqua Medic Denigran. It is made from biodegradable plastic that's uses special bags designed to give low flow rate over the me