Winterizing black tank?

[brianb]

I tried searching for this but saw nothing specific mentioned...

I try to keep my black tank "wet" at all times, with 2-3 gallons of water (and OdoBan) in there to avoid any remaining waste getting stuck/stinky. I do this to some extent on the grey tank too but not as concerned on that one. I have read this is good practice with the black tank (leaving it wet).

Anyway, what do people do when winterizing the holding tanks? Fresh tank I know to drain and leave open. Grey I was just going to drain. But for the black should I drain and add 1-2 gallons of antifreeze? Or just drain and leave dry for the winter?

Thanks for any help...

[The_Stuff]

id drain it all and then do the normal antifreeze winterizing then add your leftover to the black and grey tanks for the winter. dont want water down at the valve levels to freeze them up and bust!

[j2detroit]

we bought one of those nifty little deals you put on a garden hose and run it down through the stooll and rinse the heck out of it I then close the tank valve fill dump and refill shut down water when it comes out nice and clean then turn of the water and let it drain and leve it open and unpluge for the winter a small amount of aniefreeze will go into it from dolng the water lines in the stool has woorked for me for a lot of years

[MtnGuy]

For me, I try to get it completely drained. I will flush and blow the lines to the toilet 1st, so no water/antifreeze mix will be in the tank. My the discharge line comes out the back middle of my black tank, so I jack up the front of the trailer to drain as much as possible. I will then drive around a bit, so hopefully any water left in there will drain to the discharge line. I will then drain that line.

[SaskCampers]

We flush our tanks then I run the antifreeze through the system and what ends up in the black tank is all it gets. That will in turn run down to the gate valves to keep them from freezing. Been working for as long as we have had trailers and we hit -35 or so every winter with no issues.