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Old 05-06-2013, 11:03 PM   #1
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Gray and Black Tank questions

OK a newbie here when it comes to Gray and Black holding tanks. Just
picked up a new trailers and have not had our shake down trip yet.

So listening to my dealer and reading online I get a few different opinions.

So from what I am reading .....

When camping at a full hook sites.

Keep your black and gray tanks closed. Then as they become 2/3 full you
empty the black tank first. Then using a wand you can clean your black tank some more with several flushes.

Next empty the gray tank, which should have been closed. Keeping it open you can use your sink to run some clear water.

Once both are empty shut the values off and put the treatments in the black tank again.

Have I miss understand anything on the care of these. Please let me know how to care for these tanks.


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Old 05-06-2013, 11:07 PM   #2
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Pretty much correct except the tank flush. We have a built in flushing system and I've only used it a couple times in 12 years and never had a problem with any build up.

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Old 05-06-2013, 11:19 PM   #3
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Look up Geo-method much cheeper than buying products from rv centers. Uses calgon and liquid soap. We have used this method for 2 years and no smell etc. Also you gauges will not be all that accurate but you will figure out how long between dumps in no time
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Old 05-06-2013, 11:30 PM   #4
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Do a search for the GEO Method, I've been happy with the results. I like using a clear plastic extender that attaches between the clean out and the stinky slinky, this way you can see when you've have rinsed enough water through the tanks. Even though I have the tank flushing system, I still like to use the wand down the toilet on my final rinse before going back into storage. Lastly, keep some hand soap near by to use when your done. Have fun!!
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Old 05-07-2013, 09:04 AM   #5
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The black tank dictates everything. What is more realistic is the gray tank fills up many more times than the black tank.

When getting ready to dump the black tank I will take an extra long shower to make sure gray tank has plenty of water if needed.

I wait until black tank shows full. Why dump early when staying at full hook-ups?
I open gray tank 1st for a few seconds. This wets the sewer hose. Then open the black tank until empty. I leave the black tank open while I use the black tank flush for 1 or 2 minutes. (This is where you would use the wand). Then close the black tank. Add 3 or 4 gallons of water and then add chemicals. Then open the gray tank to clean the hose.

I use the black tank flush since it is easy to use. I think it helps keep the tank sensors working better.
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Old 05-08-2013, 06:47 AM   #6
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Originally Posted by gazingm42 View Post
When camping at a full hook sites.

Keep your black and gray tanks closed. Then as they become 2/3 full you
empty the black tank first. Then using a wand you can clean your black tank some more with several flushes.
No need to flush the black tank with a wand every time you dump. It won't hurt anything, but it's time consuming and not necessary. When on trips of less than two weeks, we never use the wand until we get back home and prepare the RV for storage.

When dumping the holding tanks at campgrounds, after the black tank is empty, we run a gallon or so of water through the pottie to wash out any remaining solids in the bottom of the tank. Then we drain the grey water tank to flush out the hose. Then close the drain valves and flush the pottie for 15 seconds or so to get some fresh water into the black tank, then add the de-stinkum.
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Old 05-08-2013, 08:40 AM   #7
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I like using our Valterra 45 degree clear flushing elbow. Let's you back-flush into the tank. I back-flush maybe 5 - 7 times before it clears up. The clear elbow is nice because you can see if there is any more solids and tp coming out. And on the gray tank you can see when the tank has stopped flowing.

We bought the flushing wand and used it once. Too much of a bother. We also have the built-in flush setup but have not used it. The GEO method has rave reviews but we have not tried it. There's the bag of ice trick on the way home to help clear the black tank. Tried it once but did not seem to work. Don't skimp on using water before and after sitting on the john and dropping your solids into the tank, you need lots of water to move the solids out of the tank and through the hose.

We installed Horst probes on our black tank on our last TT and they sure worked great (no more false readings). Bought a set for our new TT but we have an enclosed underbelly and I can't figure out how to get in there without major surgery.
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Old 05-08-2013, 08:52 AM   #8
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I think you've got the basics down but you'll develop your own preferences as you gain experience and learn how to do things in a manner which works best for you.

A couple of thoughts though:

*Do check out the Geo Method. You really don't need to be adding black tank chemicals at all if your tank is properly maintained.

*As mentioned, your grey tank will fill far more rapidly than your black tank so you'll often times be dumping only the grey tank.

*I try to never have both the black and grey tank valves open at the same time to avoid black water getting into the grey tank. Probably no rational explanation for doing this, but I'm kind of weird about that stuff.

*As mentioned, add some amount of fresh water to your black tank after dumping. I want to always have some liquid in there to help suspend the solids.

*Buy a good pair of rubber gloves to keep in your plumbing bay and wear them when handling the tank dumping duties. A bottle of hand sanitizer is a good idea too.

*When stowing your slinky hose, disconnect from the rig first and elevate the hose in order to drain all the liquids possible into the CG drain before disconnecting the hose. I like the slinkys which have caps to put on both ends for storage. Doesn't allow hose water to bleed out into the bay while traveling.

Best of luck.

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Old 05-08-2013, 12:37 PM   #9
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I flush my black tank every time I dump. I have a tank flush connection and use a seperate hose so it just doesn't take that much time or effort.
Your sequence is correct, black tank first, flush if you want, then the grey. If you have full hook ups and will be at one location for an extended period you may leave the grey tank open, then close it a few days before leaving so you have about 2/3 tank. You always wand to use grey to help clean out the sewer hose.

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