Abstract: A fluid treatment system and method of aligning and securing mechanical components within the system. The system comprises a container base with vertically extending sidewalls forming a sump, and a tank retainer disposed on the base within the sump. A system plate encapsulates the sump, and may include a bridge member projecting from the plate's top surface. A media bottle's bottom surface is placed within the tank retainer, and the media bottle's neck is received by an annular collar of the system plate such that the media bottle is secured within the system and movement of the media bottle within the sump is inhibited and/or restricted.