Fig. 2. Colloid-mass flux as a function of time, where black circles, white squares, and black triangles represent mass-flux values measured during P₁, P₂, and P₃, respectively. The gray lines connecting data points are provided only to indicate the sequence of colloid-mass flux values with time. Times of intervention are indicated with vertical, black lines labeled as INT₁ and INT₂. The decrease in the mass flux at about 2300 h may be linked to the eventual failure at about 2400 h of the pump that delivered inflow solution to the top of the core.