The Biotube Effluent Filter is designed for use in septic sysrems. It is a filter that helps to remove waste and impurities from the water, promoting a clean and healthy environment for aquatic life. This filter is specifically designed to be used in a biotube system to effectively filter out any excess waste and maintain water quality. Contractor salvage sale. Ex excavator getting rid of things couldnt throw away. Look in yhe store for other treasures.