Join Date: Sep 2004
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Re: Leave Water Tanks Empty or Full?
I think I'd leave them empty. If you have a way to flush water through the tanks before using them it would help a lot. If you can't easily flush them, at least you'll dilute the any foul contents with a full tank of fresh water. Keeping the insides of tanks and water lines "in the dark" will help reduce algae growth. A lot of the water hose sold today is transparent which doesn't help.
You keep fuel tanks full when the boat is in storage to prevent condensation from putting water in the fuel (which is a big contributor to the algae problem). Full tank = little air in tank = less water vapor = less condensation. Another thing you can do is put a ball valve in the fuel tank vent line and close it when the tank is not in use. That helps lower the turn over of air in the tank.