From manual, it is not recommended to put detergent inside… coz if got any residue, it is difficult to clean it. The hole very small and you can’t really clean inside.

Been using the 1c for 1 month… really satisfy with it. Probably the smartest gadget I ever buy. it can map the house, zone cleaning, auto reclean any part that it missed, smart routing (can move diagonally using the shortest path back to base!)