The Reusable Respironics REMstar™ Plus, Pro And Auto Foam CPAP Filters filters can be cleaned by using warm soapy water and should be cleaned weekly. There are two filters in a pack. Depending on the user’s surrounding environment may need to be cleaned or replaced more frequently. It is not the same for each user as each user has a different environment inside and outside of their home. Keeping a clean filter will extend the life expectancy of the machine as well as provide the user with the cleanest air possible. A dirty filter will cause a machine to work harder when retrieving the room air to provide the positive air pressure and if overworked too long, could cause the machine to fail.