Dual dump tanks - Event Date: 07 May 2018 - 14 May 2018

Great advice.  That was a question I didn't even know I had!  

Welcome and congratulations! Yes, I concur on leaving the gray connected and open while at a campground with full hookups. Since you are already experienced with TTs, you should already have a good idea of how to deal with the black tank to keep it from having issues. One caveat to the above advice though is if you intend to dump the black tank on leaving, close the gray tank valve and let some liquid accumulate in the gray tank so it will be available to flush out the hose after draining the black tank.

You just drain one tank at a time, black first, then rinse the hose with the grey.  I suspect you are asking about how to manage sewage while at a full service campground, with sewer hookups.  In that case, leave the grey hooked up to the sewer and let the black tank fill at least half way before draining it.  The momentum of all that stuff rushing out will help move it out.  You don't want to leave the black tank hooked up to the sewer or the tank will tend to crust over.  Yuck.  Sorry.

It's pretty easy to go a week without dumping the black tank.  With the grey hooked up to the sewer you can take as many long showers as you want!

TT