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Old 07-02-2011, 09:14 AM   #1
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to drain or not to drain, that is the question.

I have only taken my trailer out twice since I purchased it 2 months ago and am still learning the ins and outs to camping. when I hookup my sewer, do i leave the black tank valve open or closed. I've heard some say closed and then drain after it is full. Others have said that you could just leave the valve open.

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Old 07-02-2011, 09:20 AM   #2
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Never ever leave the valve OPEN when camped for either tank. Paper and other junk will stick to the bottom and start creating a mountain of "You know". You want some water / liquid at the bottom of the tanks to keep things from sticking / drying out. The manual that came with my MH clearly states to keep them closed and let them get at least half full before dumping, adding water at dump time if needed to help flush anything in the tanks out. Then dump black then gray so the gray flushes out the sewer hose.

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Old 07-02-2011, 09:32 AM   #3
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I would leave it closed until the tank is 2/3 to 3/4 full. Add some tank chemical to keep it from smelling and help digest the solids. If you leave it open all the liquid drains immediatly and the solids generally get stuck to the bottom. There is no chance that the solids will digest and may very well get stuck and baked to the inside of the tank in hot weather. Once things are stuck to the tank bottom and walls it's a real ordeal to get them free. Anything left in the tank during long term storage is all but impossible to remove. Some people refer to the solids that aren't removed as "The Dreaded Brown Pyramid". If you've ever experienced it you'll never forget it. The combination of liquid and solids will drain much faster. Then it takes less time and water to flush the tank for storage.

Before we bought our motorhome we rented a few. One had the dreaded affliction. When we returned it the rental company tried to charge us extra to clean it out. It took some doing to get them to understand that it was something that had been built up over time, it didn't happen in 1 weekend.
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Old 07-02-2011, 09:42 AM   #4
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Always leave the black tank valve closed, use plenty of water, dump when tank is 1/2 to 3/4 full and never leave waste in the tank between trips. It's a good idea to add about 5 or 6 gallons of water and some Dawn dish detergent and some water softener to the gray and black tank before heading out on a trip to help clean the tanks and dump when you get to your destination.
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Old 07-11-2011, 08:19 AM   #5
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Smile Ref: To drain or not to drain

I can attest to the fact that the build-up of "matter" is tough to clean out. We have a 30' Terry TT that we purchased used and it came with the "brown pyramid". After an eternity of flushes, we were finally able to clear it completely of "materials". Now we always wait until it is at least 1/2 to 3/4 full before draining and we also add about 4-5 gal of water after draining and add our deoderizer and bacteria agent to get the process of breakdown started for the next trip. Since doing this we have had no problems, in fact we just completed a week in the camper with (4) people and made it the entire week without having to dump until leaving. We also always open the black water first while draining and let it completely drain before opening the grey water valve. This helps flush the hose and drain using the sink water. You will find the process much simpler than expected once you follow a normal procedure.
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Old 09-12-2011, 08:43 PM   #6
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Haven't seen mention of this but when we bought our camper, our friends (camper vets) bought us as a 'gift' a clear plastic 45-degree elbow that connects the drain to the hose. Although not fun to look at, I like the fact that I can tell when all the debris has exited the black water tank. When I drain, I take the hand-held hose from the shower and put it into the toilet. I'll then open the drain valve until the majority of the tank is emptied, close the valve for a few minutes to let it fill up again, and repeat the process until no more solids are evident through the clear plastic connector.
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Old 09-12-2011, 08:58 PM   #7
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Originally Posted by RJay View Post
Always leave the black tank valve closed, use plenty of water, dump when tank is 1/2 to 3/4 full and never leave waste in the tank between trips. It's a good idea to add about 5 or 6 gallons of water
I've left the black tank partly full for months with no problem, but what do I know, I'vew only been RV'ing since 1957 and have NEVER had a tank blockage. But then, in 1957 most RV's didn't have waste tanks!!
I do add 5-6 gallons of water and chemicals to the black tank, the grey I never add anything to.

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