Filter the slurry in the lab at temperature to remove the suspended solids and evaporate the mother liquor to dryness to get a LOD and then calculate the percent water. Also, you should have a solubility curve and density of the slurry and mother liquor versus temperature that should allow a water calculation.

It is puzzling why you are getting such variable yield and size distribution--this should not happen on a batch system if the feed and operating conditions are the same.

However, sugar compounds are subject to variable and high supersaturations.