[tsubaki]

Yes but you can't depend on it, it will take trial and error also some compromise as to valve locations and hose routeing.
In the instance I have finished you can draw between two tanks by putting the switch half way between P & S.
This will not be perfect but feasible.
Correctly done both hoses must be the same length and fastening manner to achieve even flow rates. No hoses coiled or riseing or falling different than the other.
Best location would have been the forward center backsplash for the valve and then run to the filter and motor.
I was unwilling to have the valve at that location for fear of damage so I compromised correctness for a more utility aspect.
I expect to always be adjusting the valve handle to get reasonabily close or just run a while on one tank and then swap to another.