In a lab float test, you adjust to agitator’s RPM based on the volume of the tank you’re working with.  Here are suggestions.

Rougher Cell:
Total cell volume =3.3 liters
Slurry volume = 2.5 liters (until this mark slurry filled) –> I use 1000 g test charges

Cleaner Cell:
Total cell volume =1.75 liters
Slurry volume = 1 liter  I use whatever the rougher conc charge is.