Aqua Medic Deniballs are made of a special biologically produced plastic material. In the absence of oxygen bacteria metabolize the material. The bacteria are used for the reduction of nitrates, thus reducing nitrate to nitrogen gas. One to three packages (0,8 l) is enough to supply the Nitratreductor as an only food source for 12 months. It is recommended to change the Deniballs after the 12 months to ensure safe and maintenance free denitrification in fresh and seawater aquariums.Do you have questions about this article ?