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An alum dose of 65 mg/L is considered to be an over dosea slight overdose. Image Modified
Figure 1: Effluent Turbidity vs. Time, Floc Blanket on Low, Alum dose = 65 mg/L
!FB high alum dose 65 mgl.png|width=850px,align=centre!
Image Added
Figure 2: Effluent Turbidity vs. Time, Flock Blanket on High, Alum dose = 65 mg/L

Conclusions

For the Floc Blanket floc blanket at both the lower and higher levels, the capture velocity of .058 mm/s produces a lower effluent turbidity than the Vc = .116 mm/s, and Vc = .174 produces a higher effluent turbidity than Vc = .116 mm/s, which is expected.  However, Vc = .231 mm/s produces a lower effluent turbidity than Vc = .174 mm/s.(Your figures 1 and 2 on this page are the same. Please find which is which and put in the appropriate figures. Specify what you think is happening between 0.231 mm/s and 0.174 mm/s. You've seen this before. We also see a decrease in turbidity at the end of the graph. It seems like something is going on here that is predictable.)  This is not consistent with what should have happened, and cannot be explained by floc particles rolling up the settler tube into the effluent.