A chemostat with cell recycle is shown in the figure. The feed flow rate and culture volume are F = 75 L h⁻¹ and V = 200 L, respectively. The glucose concentration in the feed C_S0 = 15 g L⁻¹. Assume Monod kinetics with specific cell growth rate μ_g = (1/C_C) (dC_C/dt) = μ_m C_S / (K_S + C_S), where μ_m = 0.25 h⁻¹ and K_S = 1 g L⁻¹. Assume maintenance and death rates to be zero, input feed to be sterile (C_C0 = 0), and steady-state operation. The glucose concentration in the recycle stream, C_S1, in g L⁻¹, rounded off to 1 decimal place, is _________.