Determine the clean filter head loss in a filter bed composed of 0.3 m of uniform anthracite (with an average size of 1.6 mm) placed over 0.3 m of uniform sand ( with an average size of 0.5 mm) for a filtration rate of 160 L/m^2.min. Assume that the opening temperature is 20 degrees celcius. Use the Fair Hatch equation.