That is how a plating process works, you put the metal you want to plate, and a piece of the metal you want to plate on it in a conductive liquid, then pass a current
through. Since you are not in a sealed container the water
flow must be about zero in the vicinity.
It seems to me like it would be an advantage - you now have magnesium plated underwater metal parts
so if any electrolysis
is to occur it will have to take the plating off first. It should also extend anode life since the metals will now all be at the same potential and current
will drop to zero.