Filter materials serve various purposes: they either filter suspended matter out of the water (mechanical filtering), provide settlement space for bacteria that break down pollutants (biological filtering), or remove harmful substances from the water (chemical/adsorptive filter materials). Of course, mechanical filter media eventually become biological filter materials after a while.
The filtering should always go from coarse to fine inside the filter, as fine filter material clogs too quickly at the beginning. A coarse filter sponge or filter ceramic (JBL Cermec) is ideal for the first filter stage. For biological filtering, JBL Sintomec and JBL Micromec provide the largest possible surface area for pollutant-degrading bacteria. Activated carbon (JBL Carbomec activ/Carbomec ultra) filters out discolouration and medication residues. JBL NitratEx and JBL BioNitrat Ex filter out nitrates. JBL PhosEx Ultra helps against algae-promoting phosphate. Silicat Ex helps against silicic acid which promotes diatoms.
2 Alternatives for nitrate removal:
JBL NitratEx: This is an exchange resin which extracts algae-promoting nitrate (NO3) from the water and replaces it with harmless chloride. This is done quickly and in direct flow without any waiting time. In this way nitrate can also be removed from tap water before it enters the aquarium.
JBL BioNitratEx: Is a biological filter material on which bacteria settle after a little waiting time and then biodegrade nitrate without any "side effects". For efficient nitrate decomposition the bacteria need a carbon source (food) which is contained in the filter material. Thus the JBL BioNitratEX balls become smaller over time until they are completely degraded. Only then do they have to be renewed.