A filter element for positioning in a filter compartment of a spa includes a plastic mesh outer cylinder and a plastic mesh inner cylinder, the inner cylinder being positioned coaxially with respect to the outer cylinder to define an annular interior chamber with a filter element of annular cross-section disposed in the chamber and having keyed landings formed on the top and bottom thereof, which respectively mate and interlock with one or more keyed landings on top and bottom caps of the filter element. The apparatus may further include a plurality of vertically disposed mesh compartments interlinked in a ring and disposed within the filter element, the compartments being filled with a selected filter medium or filter media.