Interpet Internal Replacement Carbon Filter Pad Interpet Internal Replacement Carbon Filter Pad – Keep your aquarium in tip top condition with these replacement filter pads for your PF filter. They act as a chemical filtration device, removing toxic heavy metals, odours, chlorine, unwanted treatments and also water discolouration. Keep your aquarium free from dangerous invisible nasties with these Carbon Filter Pads. Also replace them every eight weeks for a healthy aquarium. Easy fit for a quick and also simple filter change Convenient monthly use also helps schedule in replacement also with other regular maintenance Specific for each model of PF Filter Box also contains 3 x Carbon Filter Pads Filter pads available: PF Mini PF1 PF2 PF3 PF4 Also click here for a wide range of Aquatic Replacement Media!