Abstract: A fluid grid system for use with filter systems and other fluid handling devices. Preferably, the fluid grid system is designed such that components thereof may be readily connected to each other without the use of clips or other fasteners. Further, the fluid grid system preferably allows components to be installed and held in place or removed merely by applying a sufficient force to a portion of the component.

Abstract: Air grid systems for distributing a gas within treatment systems such as underdrain filters and contact clarifiers is disclosed. The air grid is supported from above so that it can be lowered into position and thus modified or repaired. Additionally, this feature permits retrofitting an air grid into an existing system, such as an underdrain filter, in which the bed of media overlies the underdrain is not upset by the installation. Thus, methods of installing or retrofitting air grid systems are also disclosed. In another aspect of the present invention, the air grid is comprised of an air manifold connected to air laterals by a spreader conduit that is inserted through a smooth bore in the walls of the manifold, thereby providing a simple and easy to manufacture structure that avoids problems found in prior art components.