My question is, could there be any issues running vinegar through the head and into the holding tank? Knowing that it is virtually impossible to get our holding tank pumped out completely and that there are various deodorants and head additives.............
Using vinegar to prevent mineral buildup in the hoses won't cause any problems in the tank unless you're also flushing bleach, pine oil cleaners, or household chemical toilet bowl cleaners--which you shouldn't be using anyway because they're destructive to the rubber parts in the toilet. Combing chlorine and vinegar creates toxic chlorine gas, the same stuff used in chemical warfare, even more lethal than chlorine + ammonia. If you want to google "vinegar + bleach" and "vinegar + toilet bowl cleaners" you'll find all kinds of interesting combinations that anyone with any sense would avoid combining.
About those "...various deodorants and head additives..." Not all those should be combined either...so just what all are you using???
Because pumping out the tank always leaves an inch or two in the tank, it's important to thoroughly rinse out the tank 2-3x/season...every 3 months or so if a live aboard or you use the boat year round--and especially when prepping for winter or other extended layup. It's not hard to do and you don't have fill up the tank to do it. Just put a few gallons of clean fresh water into the tank via the deck pumpout fitting--'cuz that sends the water into the bottom of the tank to stir up any sludge and hold in suspension so it can be pumped out...pump that out. Repeat...repeat...till you're pumping out clean water. If you can take the boat offshore outside the the "3 mile limit," you can use a washdown pump to supply the water...once there are a couple of gallons in the tank, turn on the macerator pump and let it run while you continue to let water run into the tank.
