JBL UniBloc is a biological filter foam cartridge for clean and healthy water for the JBL CristalProfi internal filter i40. A fine-pored foam cartridge for effective mechanical and biological filtering. The pore structure selected provides ideal conditions for the development of colonies of cleansing bacteria which are essential to breakdown pollutants and at the same time ensures good mechanical filtering. The accumulation of various invertebrates an the surface of the cartridge adds variety to the diet of young fish.JBL recommendation: Cleaning: approx. Every 1-2 months in lukewarm water (25C). Replace the old foam cartridge after cleaning 2 to 3 times. Prime new or cleaned cartridges with JBL FilterStart Cleansing bacteria.Filter foam cartridge suitable for the JBL CristalProfi Internal Filter i40. The Cartridge is also suitable for JBL TekAir.