# Black Tank Sensors



## jcnsue (Nov 12, 2008)

2008 outback 23RS used about 15 times so far. No problems, except the last couple trips noticed the black tank sensor shows 2/3 full when empty. When it does fill up it does read full. We only use the black tank for liquids, no solids. RV toilet paper of course. Obviously I have some stuck on the sensor. What is a preferred way of loosening it up or has anyone else had this issue. Thanks.
Going out this weekend so a fix would be nice.


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## john7349 (Jan 13, 2008)

This problem happens a lot. This might work:
After you dump your tank, add a bag or two of ice and fresh water. Let it slosh around till you get close to home. Empty tank and hopefully things should be good to go.


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## Camping Fan (Dec 18, 2005)

It's a common problem, so much so that if you really want to know how full your black tank is or isn't, you're probably better off just using a flash light to look into the tank when you flush the toilet rather than depend on the sensors. A lot of people add a couple cups of liquid Calgon to the black tank, it slicks up the sides of the tank and helps keep "stuff" from sticking. You can also try dumping a bag or two of ice into the black tank before leaving home, then dump the tank when you can get to your destination. You can also use a Quickie Flush, Flush King or Sewer Solution to back flush the black tank and get crud off the sensors. The Quickie Flush and Flush King require installation into the tank, the Sewer Solution connects to your sewer pipe.


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## rdvholtwood (Sep 18, 2008)

We have the same issue with our 250RS. I recently purchased a Flush King (see pic below) from Camping World and will be using it this weekend to give the black tank a good flush. I have also heard members say that they have poured left over ice from their coolers down their toilet. The ice supposedly acts to break up anything stuck in the tank.


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## jcnsue (Nov 12, 2008)

Ice is a really good idea. We will be leaving thursday evening. I will try a couple bags and a couple gallons of water also. The drive is about 3 hours. Cross my fingers. If you hear me yell from mid-missouri, it worked. Be back sunday to reply. Never thought of the flashlight idea. Will have to try that just to see for myself!
Thanks,
jim


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## Braggus (Aug 8, 2010)

Had the same problem in our class C, we tried all the chemicals to get the problem solved but none worked...ice did the trick...


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## thefulminator (Aug 8, 2007)

I'm not so convinced on the ice trick actually does anything. The bottom of the black tank isn't flat, it's slopes down to the drain. Unless you are pulling some high G maneuver turns, the ice isn't going to move around to scrub the tank. After I dump the tank, I just add about 5 gallons of water to the black tank and dump again at a rest area on the way home. I do the same thing with the grey tank.

I had similar problems with false readings. Since I installed a Camco Tornado Rinser, I don't see the wild fluctuations in black tank levels any more. I'm not saying that the indicators are accurate but are consistent.

My 40 gallon black tank pretty much reads as follows:

(4) gallons = 1/3 full
(14) gallons = 2/3 full
(30) gallons = full

This means I don't panic when it first says full. If I really want to be sure of the level, I just push the foot pedal on the toilet and look to see how high it is.


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## Tangooutback (Apr 16, 2010)

thefulminator said:


> I'm not so convinced on the ice trick actually does anything. The bottom of the black tank isn't flat, it's slopes down to the drain. Unless you are pulling some high G maneuver turns, the ice isn't going to move around to scrub the tank. After I dump the tank, I just add about 5 gallons of water to the black tank and dump again at a rest area on the way home.


Do rest areas have dump stations?


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## CamperAndy (Aug 26, 2004)

Tangooutback said:


> Do rest areas have dump stations?


Depends on where you are bu most do not.

This is a web site with most of the dump stations RV Dumps.com


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## thefulminator (Aug 8, 2007)

Tangooutback said:


> I'm not so convinced on the ice trick actually does anything. The bottom of the black tank isn't flat, it's slopes down to the drain. Unless you are pulling some high G maneuver turns, the ice isn't going to move around to scrub the tank. After I dump the tank, I just add about 5 gallons of water to the black tank and dump again at a rest area on the way home.


Do rest areas have dump stations?
[/quote]

Many in Washington State do.

Oregon too. See highlighted in attached image or for full list see Linky.

I have these printed to fit on letter size paper, laminated and kept in a binder with all the warranties and manuals for the trailer. The binder is stored in the Outback just in case of emergency.


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## brian j (Nov 24, 2009)

i used to have black tank problems when i first got my outback which stemmed from it being a used outback and my newbie knowledge of black tanks. after following many of the best practices like only dumping when full and flushing the tank after dumping the problems have gone away.


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## rdvholtwood (Sep 18, 2008)

I’ve been pretty good about refilling the black tank with about 5 gallons of water after dumping the tanks; however, a few times I didn’t and let it go for awhile. I think thats what is causing my problems. At this point, I am not sure if a few good backfills will resolve it, but, actually adding ice to the 5 gallons of water that I add to the tank. The roads in PA, at least in Lancaster County tend to be curvy and some back roads are pretty bumpy. I’ve arrived at campgrounds with some items in the trailer knocked around - there is no doubt that the ice would help... I think this weekend I am going to try both -using the Flush King and adding ice - and see what happens.


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## Tangooutback (Apr 16, 2010)

I think if you make big block of ice in your fridge and then break them with hammer, that would provide chunks of ice with jagged edges...good for cleaning. Store bought ice has nice and smooth edge, it does not scrape as well.

Perhaps filling it with water to almost full and drop a few small catfishes in there. Them cats will clean it out in a week or two...


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## thefulminator (Aug 8, 2007)

Ever seen the Dirty Jobs episode where they were at the fish farm in the Mojave desert? Tilapia were the fish of choice for shall we say, septic cleaning. Think about that the next time you are at the seafood market or restaurant.


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## raynardo (Jun 8, 2007)

Tangooutback said:


> Do rest areas have dump stations?


Some (a very few) do.

But overwhelmingly, I've been seeing entire rest areas closed due to budget cuts. This was really evident on our 12K mile trip around the U.S. this past summer.

*Article #1*​*
*​*Article #2*
​


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## Tangooutback (Apr 16, 2010)

thefulminator said:


> Ever seen the Dirty Jobs episode where they were at the fish farm in the Mojave desert? Tilapia were the fish of choice for shall we say, septic cleaning. Think about that the next time you are at the seafood market or restaurant.


Hmm...I just had lunch at a seafood restaurant today with a group of co-workers. Several of us had Tilapia sauteed in butter sauce. Man, it was good....now you spoil the appetite...


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## Calvin&Hobbes (May 24, 2006)

I was assigned to Search and Rescue for a couple of years, and on one shallow dive, looking for victims of a traumatic boat accident.... Well, lets say I lost may desire for lobster for awhile.


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## CdnOutback (Apr 16, 2010)

Now.... there's a segue if I ever saw one....


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## Tangooutback (Apr 16, 2010)

Calvin&Hobbes said:


> I was assigned to Search and Rescue for a couple of years, and on one shallow dive, looking for victims of a traumatic boat accident.... Well, lets say I lost may desire for lobster for awhile.


In the end it is protein regardless of the source.....


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## rdvholtwood (Sep 18, 2008)

rdvholtwood said:


> I've been pretty good about refilling the black tank with about 5 gallons of water after dumping the tanks; however, a few times I didn't and let it go for awhile. I think thats what is causing my problems. At this point, I am not sure if a few good backfills will resolve it, but, actually adding ice to the 5 gallons of water that I add to the tank. The roads in PA, at least in Lancaster County tend to be curvy and some back roads are pretty bumpy. I've arrived at campgrounds with some items in the trailer knocked around - there is no doubt that the ice would help... I think this weekend I am going to try both -using the Flush King and adding ice - and see what happens.


Well didn't add the ice, but, just got finished using the flush king and it worked great. For our 30gal tank in the 250RS it took about 6 min to fill the tank. After the first flush, I filled the tank again and monitored the level from the control panel. From what I could see looking down into the tank with a flashlight, it looked like the sensors where working fine. Definitely would recommend the flush king as an alternative if you don't have a flush system installed already.


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## windwill (Sep 10, 2015)

I thought I'd share my recent experience with fixing my black tank sensor reading 1/4 full when I know it was empty. After our last trip of the year last fall, my black tank read 1/4 full. This was our last trip, so before I winterized it and stored it for the winter, I filled the black tank up one last time to flush it out. After dumping the water it still did not read empty. So when I took it out of storage this spring, the sensor still read 1/4 full. I had to take it somewhere for maintenance, so before I did, I filled the black tank up with about 25-30 gallons of hot water. I then added a hot water mixture of two cap fulls of Calgon water softener and two dishwasher packets and dumped that down the toilet. I also added a port o pak. I then drove about 20 miles and left the camper there overnight. I picked it up the next day and drove back 20 miles. When I got home, I pulled up to the closest sewer and dumped the tank (probably not supposed to do this, but whatever). It worked. Tank now reads empty. In the past I tried the same procedure, but I used the Thetford RV Level Guage Cleaner and that worked, but I think I'll try doing the same thing next time since it's cheaper.


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## thefulminator (Aug 8, 2007)

The black and grey tanks in the 250RS were giving us trouble. They always showed 2/3 or full even when empty. Last year, when I brought the trailer home before our first trip, I used Thetford Level Gauge Cleaner in both of them. I dumped it in, filled the tanks to full measuring with a five gallon bucket filled in the bathtub and let it sit for four days. When we took off I dumped the tanks at the local rest area with a dump station. They worked fine all summer.

https://www.amazon.com/Thetford-Level-Cleaner-24545-Bottle/dp/B0006H93FA/ref=sr_1_1?ie=UTF8&qid=1495157307&sr=8-1&keywords=Thetford+Level+Gauge+Cleaner


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## fjr vfr (Apr 6, 2016)

I never look at the black tank sensors....why? Just look in the toilet when I flush, so it doesn't matter if they work right or not. I do however have problems with my gray water tank! There is no way to look inside. When I guess wrong it just comes up in the tub and sticks up the place. My plan when I get caught up is to install some Horst Miracle probes. Just need to find the time.


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