Sulfur Pearls – 5 ltr. are used as filter medium for sulphur denitrification reactors. Our sulfur pearls are sulphur beads formed from pure sulphur for use in our Sulphur Nitratereductors. They are used in sulphur nitratereductors as the filter medium and energy source for the bacteria. They have to be replaced from time to time as they are slowly consumed by the bacteria. Caution: Use only in nitrate removing anaerobic filters having a low water flow rate.