2010 Fuzion 405 Holding Tanks

[debob22]

Recently bought this unit used and got back from our second trip. This is the first time owning a unit with a second bathroom. When dumping the tanks I first opened the black water valve and after that had drained I then opened the grey water valve and drained that tank. I hooked up the tank rinse before discovering a third valve hidden behind the living room slide marked grey water. The toilet in the second bathroom overflowed which of course caused a real mess to clean up also had black water come up into the kitchen sink. My questions are; do I open up the third valve for the second bathroom first and let it drain then open up the main black water valve? And, why is this third valve marked grey water when it was black water that backed up while using the tank rinse? I am really confused and don't want another mess like this! Any help is appreciated!

[Jager]

There is a thread on here about some of this. Turns out that Keystone piped the extra toilet into the kitchen gray tank. Very nice of them to do this and tell you about it. Anyway I don't know that it makes too much difference if you do "extra" gray/black tank first or second. The only one I think that matters is the real gray tank should be last.