Method and system for manufacturing bulked continuous filament having tonal coloring from PET comprising: an extruder (202); a static mixing assembly (208) coupled to the extruder and comprising a housing and one or more individual static mixing elements disposed within the housing; the method and system further comprising a plurality of colorant ports along a length of the static mixing assembly such that each of the plurality of colorant ports is configured to provide colorant (204) to a polymer stream at a different location along the length of the static mixing assembly, and one or more spinning machines (212) positioned downstream of the static mixing assembly and coupled to the static mixing assembly to receive the colored polymer stream. The spinning machine(s) may be configured to form the colored polymer stream into bulked continuous carpet filament having a tonal color effect.