I don't understand what the problem is. You have an inlet which should hzve a seacock or ball valve. This goes into the head. You will need to. Plzce a vent loop either in the inlet hose to the head, or preferably between the head flush mechanism and the bowl. The vent loop is nothing more that raising the hose above the water line and then back down, continuing it's journey to the John. The outlet also must have a similar vent loop. The vent loops prevent your boat from taking on water. Lastly you would need an air vent in the outlet line. That is it. Works flawlessly.
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