enblethen wrote:
Video I looked at shows using the winterizing port. That does get to the tank.
I believe you are mistaken about that. When winterizing, you should set the valves so that the antifreeze does not go into the fresh water tank. You do NOT want antifreeze in the fresh water tank. It would take forever to get out. The fresh water tank is "winterized" by simply draining it through the low point drain.
You DO want to sanitize the tank and all the lines. So the sanitizing additives, what ever it is, should be put in through the port that fills the tank, and then pumped through the water system.