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Old 10-31-2018, 01:56 AM   #1
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Cleaning Black Water Tank

I recently purchased a used Class B and found the previous owner(s) apparently did not take proper care to flush the black water tank. Despite flushing it now with fresh water while emptying it, it appears there is a build-up of solid waste taking up about 1/4 of the tank's capacity.

Anyone know of a tried and true method of removing this kind of build-up?
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Old 10-31-2018, 04:11 AM   #2
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While our new to us coach had a similar problem, it was not as severe as you have described. It took us a while, but we used water, lots of water, and dish soap. When traveling, we kept about 1/3 to 1/2 tank full of water with soap, and then emptied it at the next stop. It took quite a while, but now we can flush the tank and get a clear water rinse. Best of all, the stink is gone.

Hope your situation can be solved fairly easily.
May your smiles be many and the miles be plenty.

Karen & Allen Van Zandt
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Old 10-31-2018, 06:32 AM   #3
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You can try Noflex Good Reviews on Amazon
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Old 11-01-2018, 07:26 PM   #4
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Dish soap and laundry detergent with lots of water over and over again letting it soak to soften up a spray wand also helps and can be bought at Walmart
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Old 11-01-2018, 09:50 PM   #5
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What has convinced you of this 1/4 tank build up??

1) Can you see it by looking down toilet
2) Does tank have problems draining
3) OR is the /14 tank indicator light staying on after dumping tank

1 & 2.......use a Digester.

3...level indicators are notorious for false readings. GEO Method to clean sensors. Course they WILL get dirty again and then give false readings again and again and again

I don't even look at them

Toilet BURPS...time to dump black
Sink/Shower draining slower then usual...time to dump grey
Water pump goes Burrruup....need more water in fresh water tank
I took my Medication today. HAVE YOU?
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Old 11-02-2018, 12:13 AM   #6
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#3, and if the indicator lights are to be believed it's more like 1/2 tank that doesn't empty when purged.
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Old 11-02-2018, 12:27 AM   #7
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Originally Posted by HJCihak View Post
#3, and if the indicator lights are to be believed it's more like 1/2 tank that doesn't empty when purged.
Yeah, the sensors are notoriously unreliable. Best thing to do is look down the toilet opening with a flashlight. If it looks empty, then take a wand sprayer down that same hole and try to spray the sides of the tank really good. That should dislodge anything hanging on the sensors. On the other hand, if it really does have a bunch of solid material in it, then dump some Dawn dish detergent in, fill it up about halfway with water, and drive around a bit to agitate. The Dawn helps to dissolve the fats that are causing the "material" to stick to the tank. Then let it sit for a day or two before dumping. This gives the Dawn time to work, and also lets the water rehydrate/soften the material so it doesn't cause a big clog on the way out. You may have to repeat the process once or twice, but that should do it.
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Old 11-03-2018, 09:29 PM   #8
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I thought my blackwater tank was clean. I poured a few buckets of hot water down the toilet and then drained into a bucket. Yuck. I am thinking of adding an outdoor hot water spigot to my house. Every so often I would flush out with hot water and dump at the nearby rv dump site. I agree, I can get weird about things.
ex spec5 Mark
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Old 11-03-2018, 09:53 PM   #9
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Never had more than the pyramid of poo but the magic wand down the toilet is a significant headsup in getting ahead.
After doing all you can with the wand then do the lots of Dawn, hot water and a drive down the rough road in stop and go traffic. Wait a few days and drive to the dump station. Do you have a tank rinse? I find it to be pretty good once the tank is cleaned.
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Old 03-01-2019, 07:17 AM   #10
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Ice cubes

A suggestion from one manufacturer was to half fill the tank and then add detergent and water softener. Then add several bags of ice cubes and drive around sloshing the mixture and agitating the ice against the walls.
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Old 03-01-2019, 07:23 AM   #11
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I hear good things about Happy Camper Extreme.
Shell Bleiweiss
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Old 03-01-2019, 08:00 AM   #12
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And as a matter of preventing the proverbial shimountain,
the black tank should be left in closed until it is 2/3 or
so full, and then dumped.
Your previous owner left the black tank drain open when
camping, which allows the liquids to run out, but lets the
solids build up, and they can then become quite hard
and thus difficult to remove.
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Old 03-01-2019, 08:27 AM   #13
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Old Biscuit made good suggestions.

It is very important to keep the black tank drain CLOSED except when dumping the tank.

Driving with a partial tank is important. Agitation aids in keeping solids from settling.

Enzymatic digesters in both tanks to break things down in an eco-friendly way.

Many new RVs plumb the sink and lav sink into the black tank to quickly increase the liquid volume so you keep things from drying out or not having a enough water flow when emptying the tank.

Tank gauges are NOT accurate except when the tank is empty or overflowing.

Just a Crow's opine.....too many folks fret over the inside of their black tank. Do you fret over the status of your septic tank or the condition of your sewer lines and spend a lot of time and water flushing them?
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Old 03-01-2019, 08:44 AM   #14
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X2 on Harry Camper Extreme, at least till you get it cleaned just melts and floats...
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tank, water

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