How long should it take to empty the holding tanks?

[gtrnholm]

I was dry camping for about a week and when dumping it seemed to take a long time to empty the gray tanks. I had noticed this before but kept forgetting to ask around. This was probably the fullest the tanks had ever been, between 2/3 and full. It took the black water about a minute to empty but the gray took 8-10 minutes each. They seem to trickle water out forever with a stream about 1/2 of an inch. It seems to me the valves are not opening fully.
This is a 2011 3650RL.
Has anyone had the same issue?

 

[porthole]

Black Tank is 3" pipe. Grey tank is 1.5" pipe.
The 3" pipe is not twice as big, it actually has 4 times the volume of the 1.5"
So it should drain out that much faster. And the 3" black tank drains tend to be shorter runs.


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[mallard29s]

Our grey water always seems to take 5 minutes as a minimum. Black tank usually less than a minute.

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