The JBJ Ceramic Rings are the primary biological support for keeping toxic ammonia and nitrite at acceptable levels. Generally, the biological media should not be replaced unless detritus and waste is prohibiting the amount of exposed surface area available for the beneficial bacteria. Clean ceramic rings with the aquarium water and NEVER use tap water that can destroy the bacteria and cause you to have cloudy water.
Replace Ceramic Rings as needed or add extra for higher volume aquariums with large bio-loads.