IPETTIE Tritone/Fiumi Ceramic Pet Lotus Pet Water Fountain Replacement FiltersReplacement Period: Carbon filter needs changing every 2 to 4 weeks while foam filter needs cleaning every 2 to 4 weeks and replacing every 2 to 4 months for better water quality, mainly depending on water condition and the number of pets. Dual Filtration System: The carbon filter helps purify the water and eliminate bad odors, while the foam filter blocks out any hair, dust or food debris. Health and Safety: Made of eco friendly and non toxic