Critical metallicity for filament formation, Z_crit, as a functionof particle number and maximum Stokes number with H_p,init = 0.015 and Z_init = 0.01. We show the effect of changing q, while keeping the particle number fixed as N_p = 70 per cell. We also show the single-species values from Fig. 2 for comparison and see that the systems with more mass in large particles (q = 3) correspond to lower Z_crit values than those with q = 3.5. This is however not the case when τ_s,max = 10⁻¹ or 10¹. Given these maximum Stokes numbers (or Stokes numbers given the single-species case), the critical metallicity values are similar, independent of the size distribution exponent.