I don't think you quite understand the purpose...
of vinegar in a sanitation system. You don't use vinegar in your coffee pot to clean it, you use it to remove hard water streaks and stains. You use it for the same reason in a sanitation system. Vinegar doesn't clean, it doesn't "sweeten"...in fact, it doesn't do a thing for the holding tank...but the acidity in vinegar--white vinegar especially--dissolves urine crystals and sea water calcium carbonates that can otherwise build up in the head discharge hose, reducing the diameter and often creating clogs. That's the ONLY reason to put it down the head.So there's no point in using vinegar to rinse the anti-freeze out of your sanitation system. All you need is a lot of clean fresh water. When you start using it, put a cupful down the toilet once a week to keep the hose cleaned out.