Our pet fountain pre-filters are excellent for preventing cat hair and other debris (cat food, hair, etc.) from getting into the pump of your cat fountain, thus greatly reducing the frequency of pump cleanings. (The cat fountain itself still needs cleaning once or twice a week). The filters are made of aquarium grade foam, or sponge frequently used in aquariums, though not quite in the form we use. We have these made specifically to fit the pumps we use in our fountains.They simply fit over the pump and are very easy to remove for cleaning. Every time you clean your cat fountain, give the filter a thorough rinsing (a spray nozzle is best), with hot water, then cold water. Once in a while you might put a little vinegar in a bowl of hot water and let it soak for a bit. Then rinse very thoroughly. You can even put it in the microwave for a minute on high for absolute certain elimination of unwanted elements.A healthy water source is one of the most important elements for keeping healthy, happy cats and nothing, bar nothing, serves better than a handmade, ceramic, food safe cat fountain with proper filtration.It is often said by vets that water is the single most important element in your cats’ diet, critical to the distribution of all other nutrients throughout the body and it is vital that that water be as clean as possible. These pet fountain pre-filters contribute greatly to this so long as you keep them clean, which is easy to do. You can purchase our foam filters here.