Black Tank Monitor Strip

[Alberta and Randy]

Hello from Hull 67, circa 2015!

We are troubleshooting our black tank monitor that will only read as high as 35%. Starting with the tank empty, the monitor will display 0, all the way up to 35, and then stops no matter how full the tank gets (visually confirmed through the toilet).  We've owned the trailer for about 2 years now and we are not in the habit of pooping in it, although we have a handful of times max. The monitor started acting up last fall. We have done multiple black tank flushes, in case there was some blockage on the walls of the tank. 

Any ideas to try resolving? Is it easy and simple to replace if the strip on the side of the tank has gone bad? I can't tell if there is one strip or two (maybe only the top one is bad...).

Thanks for the guidance!

 

[Tom and Doreen]

Disclaimer: I've never had to replace one of these devices but there is interesting information on this site: SeeLevel Tanks Sensor

[Jason Foster]

How have you flushed the tank?

 

[Geronimo John]

Flushing the tank will not improve a sensor mounted on the outside of the tank.

But checking the connections and maybe cleaning off dust from the sensor may.

GJ

[Dave and Kimberly]

The explanation I've gotten is that any "crud" (lets call it) ... on the inside walls of the black tank can inhibit the sensor (your picture shows it) ability to read the content level inside the tank.   We use ours toilet freely as needed.   Occasionally while we have full hook-ups... I'll use a dedicated black tank hose and give the black tank a good flushing.   This helps break off any crud and flush it away before it becomes a permanent part of our black tank.    In addition, occasionally when I know we are going to be towing for several hours, I will first drain the tank... and then partially refill the black tank with fresh water and some Dawn dish washing detergent.   As we are driving along this solution sloshs back and forth and cleans the inside of the black tank.   

   If the tank hasn't been properly maintained it is possible that it could take a while to really get it clean again.   All this said those sensors are not the most accurate things in the world... but they should be much closer than yours appears to be.   Ours (for example) will read about 85% when it's really full. 

[Jason Foster]

3 minutes ago, Geronimo John said:

Flushing the tank will not improve a sensor mounted on the outside of the tank.

But checking the connections and maybe cleaning off dust from the sensor may.

GJ

Generally, when these sensors malfunction, it is because of residue sticking to the sensors interfering with their function.  I would fill the tank completely with water and let it sit full for a few days to help soften the residue, then use a wand style tank flush inserted into the toilet from the top to direct the pressurized flow toward the sensor.  If this doesn't work, find a kid with a really small arm.... lol.  

[Mike and Carol]

If the previous owners were not diligent with their black tank maintenance, you may be dealing with their deposits that have become a part of the tank.  Yuck.  As Jason suggested I would add before filling the tank I would throw in a detergent pod and some liquid Calgon water softener.  Also, drive around a bit to get some agitation.  If you’re going to leave it sit for a while you might try some Happy Camper, we add it whenever we’re home and our trailer is going to sit for a month or two.

After every dump we add a laundry detergent pod (whatever is cheap) and some Calgon water softener.  We usually dump at our destination, driving with some level of fullness in the black tank.  The only time we dump before we leave is if we’re going to a location where we won’t be able to dump.

When dumping, I always fill the tank to 80% or so and then do a couple of additional fills/flushes until what comes out is clear.

Good luck!  Mike

[SeaDawg]

 Old school internal sensors failed early, and always. SeeLevel is awesome,  imo. We used them in our boat, too, when we upgraded our system, based onbl their reliability in our camper.

As everyone has noted, including  @Jason Fosterthey still have to rely on sending through the wall. You said you rarely use the black tank.

Change that up, and do follow @Mike and Carol practices. DON'T  dump that black tank when only a bit full. Do add calgon, or borax mixed with warm water first, and drive it around to the next camp site. (The old school ice in the tank has never worked for us, in used rentals that we've delivered.)

If you follow Mike and Carol's procedures,  several times, with a mostly full tank ( you can see it, on visual inspection), you have a bad sensor , imo. Contact SeeLevel. 

Replacing the sensor with a poop pyramid, or unclean tank walls, will yield the same results. So, do try to clean it up first, imo.  

[Alberta and Randy]

Thanks everyone for your comments or suggestions!

Tom and Doreen - thanks for the link, that was an informative read. I need to measure, visually verify, our tank to see if it is less than 14" tall, indicating there is only one sensor strip to go out. In my troubleshooting imagination, I could see two stacked strips and the top one went bad. 🙂

Jason Foster - we use the black tank flush port (multiple times), that sprays water into the tank.

Geronimo John - I have not tried dusting the sensor, thanks for that suggestion. I'll get a can of compressed air to blow on the sensor, from a distance.

Mike and Carol - we have put Dawn dish liquid in the tank before using the black tank flush port, to help break down whatever.  We have not tried to soften the water so I can try that with borax....or driving around with a full-ish tank and dish soap & borax. We have regularly used Happy Camper for maintenance during our ownership. Two years of ownership and the readings started acting up in the last few months so I suspect this is nothing to do with the previous owners.

SeaDawg - we regularly use our toilet, just not for poop. We will try using Mike & Carol's method, with more attention to detail on where our previous methods have differed from theirs and see (hopefully, fingers crossed) if we get different results. I would much prefer to clean then replace a part, if possible.

 

Thanks again everyone for the input! We will keep plugging away on this issue until we get it resolved one way or another. 🙂

Alberta

[SeaDawg]

Good luck, Alberta, and keep us posted on results. 

[Geronimo John]

On 2/17/2024 at 1:42 PM, Geronimo John said:

But checking the connections and maybe cleaning off dust from the sensor may.

GJ

First check the connections.  If they are firm, then dusting likely will not make any difference other than it will be cleaner.  

[Alberta and Randy]

On 2/18/2024 at 9:12 PM, Geronimo John said:

First check the connections.  If they are firm, then dusting likely will not make any difference other than it will be cleaner.  

Yep, if we press slightly on the black lead wire at the connection/solder point it causes the tank reading at the monitor to jump numbers. So this may be the culprit! We are going to monitor on our upcoming trip and may end up trying to put a daub of solder back on to "tighten" that connection, if possible.

[Dave Mazone]

I once heard that partially filling the tank and then dumping a fair amount of ice into it before taking the trailer for a ride helps. Apparently the ice "scrubs" the tank, melts, and can easily be drained upon destination.

[topgun2]

1 hour ago, Dave Mazone said:

I once heard that partially filling the tank and then dumping a fair amount of ice into it before taking the trailer for a ride helps. Apparently the ice "scrubs" the tank, melts, and can easily be drained upon destination.

A number of YouTube videos have tended to disprove this approach.  But, I've never personally tried it because (as of now) I've never had this problem.

Bill