The pet water fountain requires regular filter replacements for optimal performance. Replace the carbon filter every 4 weeks to prevent mosquitoes and the foam filter every 2 months to maintain fresh water. TReplacement Filters for Cat Water Fountain Stainless Steel Stainless Steel Cat Water Fountain and allows for easy replacement, ensuring your pet has access to clean and high-quality water throughout the day. Be sure to soak the filter in a clean bowl for 5 minutes befReplacement Filters for Cat Water Fountain Stainless Steelr filtration. Please avoidReplacement Filters for Cat Water Fountain Stainless Steelcause dust build-up on the surface. Included in the package are 8 replacement carbon filters and 8 replacement sponge foam filters. Trust our filters to provide the best protection for your pet and keep their water supply clean and healthy.