JBL UniBloc is an high-qualitiy foam cartridge, medium-pored (25 PPI), for effective mecahnical and biological filtering. The pore structure provides ideal conditions for the development of colonies of cleansing bacteria. The grooved shape (T profile) allows for long use with little reduction in flwo.Recommendation:Cleaning: approx. Every 1-2 months in lukewarm water (25C). Replace the old foam cartridge after cleaning 2-3 times. For filters with several cartridges, only clean or replace the foam cartrigdes at alternate intervals. Prime new or cleaned cartridges with JBL FilterStart Cleansing bacteria.JBL UniBloc Filter foam cartridge suitable for JBL Interanl filters:-CristalProfi i60-CristalProfi i80-CristalProfi i100-CristalProfi i200