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Old 01-27-2012, 10:35 PM   #1
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Black & Grey Tank Dumping

I thought I had the scoop on the poop regarding the proper dumping protocol. Poopus Maximus of the East (the big turd next door) tells me that I should leave the black tank dump valve open after emptying it so that I can open the grey tank dump valve to have an open vent allowing the grey tank to empty without building up suction inside the grey tank. There actually do seem to be two emptying stages for my grey tank....as if some suction was building up and preventing the constant flow rate of the grey water....and I'm wondering if he's right. So....like....whaddayathink???

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Old 01-27-2012, 10:44 PM   #2
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I always drain the black tank first then close it, then open the grey. I never have them open at the same time.

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Old 01-27-2012, 10:57 PM   #3
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I keep them both open but Im also flushing the black tank while the grey is draining.
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Old 01-27-2012, 11:16 PM   #4
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I do one at a time, but don't see that it would help nor hurt.

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Old 01-27-2012, 11:28 PM   #5
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I think Poopus Maximus of the East has sniffed one black tank too many. If he has suction in his grey tank then he need to do something about his clogged vent pipe. Empty and flush your black tank, close the valve, open the grey tank valve and flush the hose with the water from the grey tank. We won't get into the great debate on whether or not the grey tank should be left open or closed. FWIW, mine stays open.
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Old 02-02-2012, 05:05 PM   #6
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I would not do it in the way Poopus Maximus has suggested for a couple of reasons.

#1. The tanks are vented and should not build up suction. If they do check for a blockage in the vent pipe.

#2. I never have the gray open when I have the black open. I do not want take the chance of cross contaminating my gray tank with any gunk from the black tank.

If I'm at a park for an extended stay I will keep my gray open until a few days before I depart. I want to make that prior to dumping I have the gray tank about 2/3 full. This gives me a good hose flushing after dumping the black.

My dump process is to dump the black first, then hook up the water supply and use a specific hose for black tank flushing only, to my black tank flushing hook up. I then let it flush the tank for about 10 min. I then close off the black tank and open the gray water tank and empty it.

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Old 02-02-2012, 05:25 PM   #7
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The question is, is Poopus Maximus perhaps on irv2 under a different name?
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Old 02-02-2012, 05:29 PM   #8
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I always dump black tank then flush close valve then open grey to flush out drain hose.
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Old 02-02-2012, 05:33 PM   #9
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Interesting subject......My black water drains super fast, but the gray water has always drained very slow. Last trip out I forgot to close the black tank valve and the gray drained very fast.

I hope to hear others comments on this subject.

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