Black water tank full?

scottknight1

Well-known member
My tank shows full even after it’s been emptied

When we flush now it spits up a little. Does this mean it’s really full?
 

rhodies1

Well-known member
If you Left the tank fill to the top ,it’s possible some of the sewage is in the pipe from the toilet to the tank causing a partial blockage.you also may have the dreaded poop pyramid in the tank below the toilet pipe.
 

david-steph2018

Well-known member
My tank shows full even after it’s been emptied

When we flush now it spits up a little. Does this mean it’s really full?
Do you leave the black tank valve opened to let the tank drain? If so, do not leave the valve opened. Close it after dumping to avoid such things as the pyramid. Also use allot of water with the black tank.
The sensors are well known for not reporting a correct status of the amount in a tank. Even after the first use, something can cling to the side of the tank creating a false reading.
When our black tank "burps", it is time to dump the tank.
I also keep my gray valve closed, to have enough water to help clean the hose after dumping the black tank.
 

JohnDar

Prolifically Gabby Member
Do you leave the black tank valve opened to let the tank drain? If so, do not leave the valve opened. Close it after dumping to avoid such things as the pyramid. Also use allot of water with the black tank.
The sensors are well known for not reporting a correct status of the amount in a tank. Even after the first use, something can cling to the side of the tank creating a false reading.
When our black tank "burps", it is time to dump the tank.
I also keep my gray valve closed, to have enough water to help clean the hose after dumping the black tank.

That’s how you do it


Sent from my iPhone using Tapatalk
 

scottknight1

Well-known member
Do you leave the black tank valve opened to let the tank drain? If so, do not leave the valve opened. Close it after dumping to avoid such things as the pyramid. Also use allot of water with the black tank.
The sensors are well known for not reporting a correct status of the amount in a tank. Even after the first use, something can cling to the side of the tank creating a false reading.
When our black tank "burps", it is time to dump the tank.
I also keep my gray valve closed, to have enough water to help clean the hose after dumping the black tank.
Bought a used big horn 3160.
Sensors have never worked. Tried the rv hose with the sprinkler. The that didn’t help.
Tried commander for 36 hours. Didn’t help.
We’re in the rig full time. I have a 300 gallon holding tank under the rig.
I leave all the valve closed. Then drain box then gray.
I’ll drain both today.
Thx
 

scottknight1

Well-known member
If you Left the tank fill to the top ,it’s possible some of the sewage is in the pipe from the toilet to the tank causing a partial blockage.you also may have the dreaded poop pyramid in the tank below the toilet pipe.
I try the rv hose with the sprinkler on the end today after I drain the tank to see if I can remove either of the things you mentioned. Thx
 

wdk450

Well-known member
The "burping" on flush is a symptom of lack of tank venting, most often caused by the tank liquid level being higher than the rooftop vent pipe insertion into the black tank. A lot of people believe that their vent pipe was installed too far into the tank by the factory installers, which can cause toilet "burp" to happen before the tank is really near full.
You may be able to go up on the roof, use a drain snake to make sure the vent pipe is not blocked at all with an emptied tank.
There are companies like this throughout the country that come to your rig and do an analysis (sometimes video snake) and remedial action: https://kleentank.com/ You may want to do your own websearch on "RV Tank Cleaning".
 

scottknight1

Well-known member
Ok. Thx ! Havent heard that before. Will look into it!
The "burping" on flush is a symptom of lack of tank venting, most often caused by the tank liquid level being higher than the rooftop vent pipe insertion into the black tank. A lot of people believe that their vent pipe was installed too far into the tank by the factory installers, which can cause toilet "burp" to happen before the tank is really near full.
You may be able to go up on the roof, use a drain snake to make sure the vent pipe is not blocked at all with an emptied tank.
There are companies like this throughout the country that come to your rig and do an analysis (sometimes video snake) and remedial action: https://kleentank.com/ You may want to do your own websearch on "RV Tank Cleaning".
Great tips ! Will get a quote.
 

rhodies1

Well-known member
I do not use the blank tank flusher on my Bighorn,I found it was less than effective in cleaning the tank.
I purchased a Valterra Flush King which hooks onto the flush pipe and back flushes the tank.When I first used it I was absolutely amazed at the amount of sewage that drained from what I thought was a clean tank.
When I’m finished draining and flushing using this flusher,my sensor for the Black Tank reads Green
 

scottknight1

Well-known member
thx... I have the flush king, but haven't back flushed with it much... any tips on how to much water to throw up line would be appreciated.... It didn't seem to bring forth much after I drained the black water....
thx again for the tip
 

rhodies1

Well-known member
I run it for about a minute each time,I flush about 6 times or until the water is clear,make sure your grey tank valves are closed as well.
 

travelin2

Pennsylvania Chapter Leaders-retired
I do not use the blank tank flusher on my Bighorn,I found it was less than effective in cleaning the tank.
I purchased a Valterra Flush King which hooks onto the flush pipe and back flushes the tank.When I first used it I was absolutely amazed at the amount of sewage that drained from what I thought was a clean tank.
When I’m finished draining and flushing using this flusher,my sensor for the Black Tank reads Green
Similarly, I can back flush our black tank using grey tank water. I ensure the grey tanks are nearly full when it’s time to dump the black tank. I close the external add on valterra valve and open both grey tank valves. The grey water rushes into the black tank. Close the grey tank valves and dump. I can usually perform this function 3 times. Agree the internal flusher does a sub par job of removing solids from the black tank.
 

JohnDar

Prolifically Gabby Member
A hint on using the flush king. To know how many gallons of water you’re putting into the tank, connect a battery flow meter (~$20 or so) to the hose.


Sent from my iPhone using Tapatalk
 

Toysrus

Member
My tank shows full even after it’s been emptied

When we flush now it spits up a little. Does this mean it’s really full?
First Q: Emptied, how? Is it clogged? There is a handy tool we bought a while back, like a wire plunger. It may not be fun, but if your toilet burps it may indicate the need for unclogging the toilet. Open wide, insert plunger all the way down, pull-up as needed. Afterward, lots of water and "empty the tank" again. I'll look for the plunger thingy and post. (ToiletShroom is the item.) About 15 bucks. Works like a champ when you need it.
 
Last edited:
Top