Easy to use reusable foam filter for hot tubs and spas. The foam filter can be used multiple times, helping you save money while keeping your tub clean and comfortable. Important chlorine guidance. Do not overchlorinate your water, as excessive chlorine can cause the foam to decompose. Always remove the filter when performing a chlorine shock treatment; removal is not for nonchlorine or oxy shock treatments. Performance relies on proper chemistry. The filter works as intended when correct chemical levels are maintained in your tub. Normal discoloration is expected. Discoloration of the filter may occur with use and is normal; it does not indicate a fault. Material and compatibility. Made from foam for durable, reusable filtration. Designed to fit standard hot tub/spa filter housings (check fit for your unit). Use scenarios Routine maintenance: After each soak, rinse the filter and reuse to extend life. After refilling or heavy use: Clean, dry, and reinsert to maintain water quality. During shock treatments: Remove the filter when using chlorine shock; no removal needed for nonchlorine or oxy shock treatments.