Clarifier insert is intended to be combined with an open-top frac tank, allowing the tank to function as a low-cost, highly efficient solids removal system for various waste streams. The inclined plate design allows the settling area, or surface area, to be as much as 10 times bigger than the actual footprint occupied by the clarifier. This significant reduction of floor space is achieved by reducing the separation between plates and stacking the settling surface at an angle. This slant plate design gets the maximum square footage with the smallest footprint possible.