Black tank always reads 3/4 full?

stormer · 06-22-2018, 02:02 PM

Well this is a new one for me. I empty the black tank, flush with black tank sprayer, let it run clear. I come inside, check the reading and it stays at 3/4 full. Bad sensor? We use the rv tp and i use the drop ins to help with break down.

doc73 · 06-22-2018, 02:07 PM

The black tanks do seem to always be off. Mine will say something other than empty until I back flush a few times then it will drop off the empty after about an hour. The stuff in them tends to hang up on the sensors or give false readings. I have learned to gauge the level either through the top or after camping lone enough you'll get a good fell for dump time. I do not dump each time only every so many trips. Also I have found the built in sprayer is not very good.

5picker · 06-22-2018, 02:23 PM

Those tank sensors are notoriously inaccurate.

Often times mine doesn't change for a couple days after emptying or ever.

In 40 years of owning campers, some worked most didn't.
Like doc73 says... you'll soon learn when the tank level is full without relying on the cheap gauge. If you use a clear elbow or extension on the sewer outlet when emptying/flushing you'll know when the flow stops and the tank is empty.

Scrapper · 06-22-2018, 02:33 PM

If your toilet belches, burps, farts or whatever you want to call it when flushing then it's time to dump the tank.

Skyliner · 06-22-2018, 02:49 PM

A flashlight looking down the toilet valve is all I need to know how full it is. As a previous poster stated, the gauges are very inaccurate. Mine reads 3/4 full even when empty.

As a practice because we conserve water when camping, we do not discard toilet paper in the toilet black water tank. We put TP in little ziplock bags and discard them in small bagged trash can and dispose of the waste every couple of days. We find less material buildup on the grey water tank with this practice.

keegantimber · 06-22-2018, 02:57 PM

After dumping and before I empty fresh tank I always put water into black tank. Always travel with some so called clean water in black tank, never dry.

BandJCarm · 06-22-2018, 03:01 PM

Mine's read 3/4 full since I bought it. Mine has two choices, 3/4 and 4/4. But I sure don't want it to ever be 0/4 full! Need water all the time.

A32Deuce · 06-22-2018, 03:39 PM

X2!

Quote:

Originally Posted by Scrapper

If your toilet belches, burps, farts or whatever you want to call it when flushing then it's time to dump the tank.

rockfordroo · 06-22-2018, 03:43 PM

Implement the Geo Method:

https://sites.google.com/site/cbruni/

stormer · 06-22-2018, 04:00 PM

Quote:

Originally Posted by Scrapper

If your toilet belches, burps, farts or whatever you want to call it when flushing then it's time to dump the tank.

hahaha! I should say so! To be honest, I was like wow, my wife must be using a lot of TP! how are we already 3/4 full?? Then I noticed yeah... something is amiss here.

Well, it seems to be a common issue with RV's... seriously haven't they figured out how to make a good sensor that is accurate yet from the manufacturer?

Thanks for the input!!

James

A32Deuce · 06-22-2018, 04:11 PM

I think cost is involved! If they put the best of everything in these things, I don't think too many could afford one!

prairiecamper · 06-22-2018, 05:25 PM

Some people say their gauge is always stuck on 2/3 but it’s really 2 turds.

Oaklevel · 06-22-2018, 05:30 PM

Never have worried about using the sensors our earlier campers did not come equipped with them, you just learned how long the tank or tanks took to fill. I still do that. Sensors are a nice idea that is not needed.

Our first camper had one tank period for both black and grey water. You definitely did not want to over fill it.

ICanFixIt · 06-23-2018, 01:48 PM

I had same issue. Flushed and flushed but never would read below 3/4. I resolved by emptying the black tank and flushing until it was clear. Put a few pints of fabric softener (some say you can use water softener instead) into the black tank via the toilet and filled to past full. Then let it set 24 hrs. If you can drive it around a bit to cause some water movement in the tank even better. Then I flushed the tank and could not believe all the crud that came out. Flushed it until the water was clear. Checked gauge and it now is accurate showing empty. Crud on the side of the tanks throws off the sensors. I think I will do this now on a regular basis as maintenance just to keep it working.

davellie · 06-23-2018, 01:58 PM

I had the same issue. The only thing that worked for me was this back flush valve: https://smile.amazon.com/Camco-Holdi...ackflush+valve

poppytoymaker · 06-23-2018, 02:17 PM

I've had the same valve for about 2yrs. I hook it up soon as I get to the campsite. Fill the tank 3 or 4 times before I leave and I'm still between 3/4 and 4/4. The answer is Horst sensors and they are only about $35.00. I don't know if I can change them myself, don't know if I want to, and my mechanic doesn't show any real interest in the job, can't say I blame him lol

dmlranhc · 06-23-2018, 03:07 PM

I have the same results and have had it with previous trailers. The black tank sensors have never been accurate. I flush like you did and it still shows the wrong reading. I don't think it ever shows empty. Wish they would make an accurate one.

Fluffywhitedogs · 06-23-2018, 04:03 PM

Every time this has happened to me, filling the tank with water while adding a cup or so of powdered dishwasher detergent, leaving it sitting for about 24hrs, then draining and rinsing has fixed it.

rockfordroo · 06-23-2018, 04:25 PM

Quote:

Originally Posted by ICanFixIt

I had same issue. Flushed and flushed but never would read below 3/4. I resolved by emptying the black tank and flushing until it was clear. Put a few pints of fabric softener (some say you can use water softener instead) into the black tank via the toilet and filled to past full. Then let it set 24 hrs. If you can drive it around a bit to cause some water movement in the tank even better. Then I flushed the tank and could not believe all the crud that came out. Flushed it until the water was clear. Checked gauge and it now is accurate showing empty. Crud on the side of the tanks throws off the sensors. I think I will do this now on a regular basis as maintenance just to keep it working.

You want to use water softener. Fabric softener is an entirely different chemical and doesn't help unless you're flushing your clothes down the toilet. I'm guessing just filling the tank is what solved your problem, not the fabric softener.

https://sites.google.com/site/cbruni/

5picker · 06-23-2018, 05:08 PM

Quote:

Originally Posted by rockfordroo

You want to use water softener. Fabric softener is an entirely different chemical and doesn't help unless you're flushing your clothes down the toilet. I'm guessing just filling the tank is what solved your problem, not the fabric softener.

https://sites.google.com/site/cbruni/

Yep.
Fabric softener is formulated to work with... well...fabrics. Not plastic and metal.

Water softener is what will help the gunk flow out of the tank.

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