An assembly for removing grit particles from a fluid having a flow. The assembly includes a tank having walls for holding fluid for separation of grit particles from the fluid, a fluid inlet for flow of fluid into the tank, a fluid outlet for flow of fluid from the tank, an inlet diffusion baffle assembly including a baffle positioned to direct fluid flow toward the tank walls and a lower chamber of the tank, and an outlet baffle assembly including a baffle positioned in a rear of the tank at an upward slope from the center of the tank toward the fluid outlet configured to direct fluid flow toward the center of the tank.