JBL filter modul complete with filter foam pad for the extension of the JBL internal filter CristalProfi m greenline. The JBL CristalProfi m Mat Filter can be expanded by additionally purchasing one or more modules. The only limit is the height of the aquarium. Please activate also the Filterpads of the modules with 25 drops of JBL FilterStart as described above. The modules can be arranged in any order. Please ensure that the base plate with the valve is always attached on the lowest module.Do you have questions about this article ?