Eheim Filter Pad Set Professional 3 This pad set consists of 1 blue and 4 white polishing filter pads that can be used in the Professional 3 250,350,600 and Professional 3e 350. Changing your filter media regularly can extend time between cleaning and make sure that your fish are enjoying the most sanitary environment. Blue Pre-filteration through foam filter pad: On account of the large upper pre-filter, the particles of dirt are extracted from the in-flowing water before the actual filteration process takes place in the filter baskets, which increases the lifetime. Fine filteration: Fine dirt particles are trapped in the fine filter pad before water re enters into the aquarium, polishing the water and providing crystal clear conditions. These pads get clogged up quickly so require regular replacement to keep your aquarium looking fantastic.