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Unlike the results for the 9.5mm tube, there isn't a sharp increase in the turbidity which would clearly indicate the critical velocity. Rather, there is a gradual . Although the turbidity of the effluent water increases, the increase in the turbidity , showing that floc roll up is happening, however it is not possible to identify the exact critical velocity from this range of capture velocities tested. Like the 9.5mm tube, the turbidity eventually reaches a plateau, indicating the point at which the maximum amount of flocs are rolling up the tube. The discrepency between the results of the 15.3 mm tube and the 9.5 mm tube is currently being investigated.
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is minimal compared to the 9.5 mm tube. Thus, there is no clear evidence of floc roll up.