The residue is more dust like and floats away if you make a curent.
I stopped using the Aquabot and went to manual vacuuming.
I backwash amd rinse after each vacuuming session.
I also shocked the pool with liquid chlorine an am running the filter continuously.
The pool water is clear with the following readings.
PH - 7.5
FC - 5 - OTO
Alkalinity - 80
Hardness - 300
CYA - 30.
Still vacuuming up some remaining residue.