Floc samples taken from batches prepared on a bench scale flocculator are repeatedly driven through a tube to and from a reservoir at a controlled rate of flow. The Floc Size Distribution (FSD) of a sample from the reservoir is determined using a light obscuration instrument for a sequence of completed strokes in approximately geometric progression. The response of the FSD to a step change in flowrate is examined by consideration of the mean and standard deviation of the distribution and the variation in total floc population. Correlations between the parameters of the FSD and the microscales of turbulence are presented. Observations on the relationships governing the mechanisms of floc disruption are reported. The splitting of flocs is not defined simply by a frequency since the mechanism fails once the remaining flocs are resistant to the most severe disruptive forces available in the system. Either detailed information regarding the floc density distribution or knowledge of the history of a particular suspension will be required to fully predict the response of a floc population to a given flow field.