Draining gray after black tank washer/black tank combo

[Taxman2436]

I have always tried to drain a near full gray tank after the black tank. We recently purchased a 2021 Salem Hemisphere with washer/dryer and the black tank shares the outlet with the washer drain. We don’t always use the washer when it is time to drain the black so wondering if anyone has a way around this.

[kellem]

Perhaps a minority here as I pull both valves " black and gray " at the same time.
What I've found is a vacuum effect is created at the Y connection and black tank has a much better disposal rate.

I do however spray out the slinky.

[Taxman2436]

Well, that makes sense. I do have the black tank flush and that will take care of it. Thanks for that!

[Lwiddis]

Don’t hesitate to fill both tanks just before dumping...black then grey...if water is available.

[CA_Traveler]

Install a tank flusher in the black tank or use a cleaning wand in the toilet.

The reason we drain the black tank first is to clear out the drain hose with the grey tank water, nothing to do with flushing the tanks.