I'll add another thought on the dumping sequence, after I experienced a shtty scenario ealier this week.
Prior to dumping your black tank, do a very short dump on your gray tank to ensure your hose / connections are sound, because it is a lot better to find out they are not with gray water than black...... Trust me, I had the coupling between my hose sections come apart when the rush of black water went down the hose
, thankfully I quickly shut the valve, and it was a grassy area. But a mess to say the least, and a lot of time to wash down the area, hoses etc. And yes, we told the staff so they could wash it down more if they felt it was needed. Can I just say YUK!
My new newbie rules for dumping the black tank.
First, check all hose connections and couplings
Dump some gray water just to be sure everything is good.
Dump black, (rince out if appropriate)