Hi Dom
Well we never came across a problem,
By attaching to a container and bypassing the main supply tank this would not contaminate it and avoid problems of flushing tanks.
Surely the flushing the hoses would not be as much problem as you mention and once flushed through you would not be contaminating any work area
You could experiment on a dosage as enough to stop equipment from freezing
It was only an idea take it or leave it
Alan