An aeroponic plant growing system includes a water reservoir and growing chambers for growing plants in an aeroponic environment. A pump, a water distribution manifold, and water lines are used to provide water and nutrients from the water reservoir to sprayers in the growing chambers where the water and nutrients are sprayed on the roots of plants growing therein. The water distribution manifold and water lines preferably are provided as closed loop systems, such that water is provided to all sprayers despite a blockage in the manifold or a water line. Non-absorbed water and nutrients are returned to the water reservoir from the growing chambers on water return lines via a filter that includes multiple types of filter media, including filter media that support the colonization of organisms that support plant growth.