Apparatus, methods and systems for preparing a polymer concentrate for treating a formation with slick water systems viscous fluid or a gelled viscous fluid are disclosed. The method includes directing a powdered gel into a vortex mixing chamber, while directing a first portion of a base fluid into the vortex mixing chamber to form partially hydrated fluid concentrate. The partially hydrated fluid concentrate is then sucked or sweep into a main portion of base fluid for form the slick water systems viscous fluid or gelled viscous fluid.