Leave them both open. The automatic switch over does the rest. It switches to the full tank when the first one go's empty showing red on the indicator instead of green. Turn the indicator to the other tank and it will show green again. Take the empty tank out and get it refilled. Pretty simple.
Some make it more complicated then necessary. Let it work for you the way it's suppose to.
X2 It works as designed
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Jason & Wendy
2014 Ford F-350 Lariat 6.7L PSD
2015 Keystone Montana 3711FL
B&W Patriot 16K Fifth Wheel Hitch