Forgive me for the idiotic question - Just got a 2310 walkaround. There is a washdown pump at the transom. Is this pumped from saltwater or freshwater? I assumed fresh water since there is a water cap/fill on the starboard side of the boat and that must be the tank for the washdown since I have no other running fresh water on the boat (no sink, connected head, etc.). So in order to the run the washdown I have to fill the fresh water tank?