Community Forums

Vibeman · 10-04-2022, 06:01 AM

Since so much is written here about waste tank sensor problems I thought some folks might be interested in seeing what they actually look like from the inside.
My gray tank sensors have read 2/3 full for the last year, regardless of actual level. I finally bought Horst sensors and started the installation yesterday. I recently bought a cheap Bluetooth borescope on Amazon too. (a really cool thing to have if you like to fix stuff) After drilling the 3/8” holes for the new sensors I went inside the tank and had a look around with the borescope. Pretty disgusting but informative. The lowest 3 sensors had maybe a 3/16” - 1/4” coating of light colored goop and had been inoperative for over a year. The top sensor would always work when the tank got that full. I couldn’t actually get a camera shot of the top sensor, but there was no thick goop coating at the top of the tank wall, it only started to get thick at around the 2/3 level. That explains the sensor readings I got. Back in April before heading back to Michigan from Texas I put a couple of cups of liquid dishwasher detergent in the tank for the ride home, on the road 4 days using the tank without dumping to try to get the sensors to work. It didn’t help. After our last camping trip in August this year I dumped the tank and then refilled it with just water and added “Happy Camper” powder. That mix was in the tank for over a month. I then dumped the tank last week but sensors still read 2/3 full. That brings me to my inspection yesterday. Once I drilled new holes next to my original (glued in) sensors I was able to bend my small copper tubing blow gun extension 90° so I could blow off the original sensors. Once I did that the tank read empty for the first time in over a year. I was surprised at how thin and soft the coating actually was, but since it was wet and goopy, I was not surprised that it shorted out the very small and short original sensors. Since I have the Horst sensors I will install and use them, but since they are easily removed I could now look around inside the tank whenever I want to see what kind of residue is present. Maybe I can find some concoction that will actually remove the goop. I could also easily switch the wires back to the original sensors at any time to check their function.
I have attached a before and after photo of one of the sensors. The before photo was taken with the camera closer to it so it looks bigger than the after photo, but the coating was actually a little less than 1/4” thick.

JNSNWT · 10-04-2022, 08:16 AM

Thanks for sharing your info. Here’s a couple of thoughts.

1. When you put the DW soap in for the ride home I wonder if it would have helped the soap work if you added a couple of gallons of HOT water each day in an effort to keep the temperature up.

2. Would some type of septic treatment work to digest the goop?

3. I bet the goop is mostly soap scum, dead skin cells and oil washed off your body.

SJ-Chris · 10-04-2022, 01:50 PM

Interesting. Is this on your 2020 RV? I'm surprised to see such a thick buildup inside the gray tank. Understandable why that sensor isn't reading correctly.

Perhaps when you dump your tank and let the RV sit for weeks/months at a time, all that coating gets a chance to harden and then becomes difficult to remove??

-Chris

Vibeman · 10-05-2022, 04:22 AM

Quote:

Originally Posted by JNSNWT

Thanks for sharing your info. Here’s a couple of thoughts.

1. When you put the DW soap in for the ride home I wonder if it would have helped the soap work if you added a couple of gallons of HOT water each day in an effort to keep the temperature up.

2. Would some type of septic treatment work to digest the goop?

3. I bet the goop is mostly soap scum, dead skin cells and oil washed off your body.

All good suggestions John, thanks. I’m not too worried about the coating inside the tank per se, only in how it disables the sensors and I am hoping the Horst sensors will solve that problem. One factor that I think makes a big difference is the water, namely HARD water. Where I live in Michigan most well water has a lot of iron and other minerals dissolved in it. We winter in south Texas where the water is even HARDER! Almost nobody even drinks the city water down there. Until now we have only used the hard water from home and in Texas in our coach so I feel that is a big factor. Hand/body soap immediately creates a scum when used in hard water and oils of course don’t dissolve in water, so you are probably correct about the composition of the coating. Also a contributing factor is undissolved fats/oils from dish washing. My wife uses Dawn and is careful about keeping solid scraps out of the tank but I’m sure it still adds to the coating. I bought a small portable water softener after returning from Texas this spring and since then I have used only softened water in the coach. I plan to use it exclusively from now on. Maybe I will go in the tank for another look around next summer.

Vibeman · 10-05-2022, 04:45 AM

Quote:

Originally Posted by SJ-Chris

Interesting. Is this on your 2020 RV? I'm surprised to see such a thick buildup inside the gray tank. Understandable why that sensor isn't reading correctly.

Perhaps when you dump your tank and let the RV sit for weeks/months at a time, all that coating gets a chance to harden and then becomes difficult to remove??

-Chris

Yes, this is the gray tank in our 2020 Thor Hurricane. We will have had it 3 years come November. I think any tank used to hold household waste will develop a coating inside, but as I explained above, I think the hard water makes it a lot worse. The coating is soft now and easy to blow off (the tank has been empty for a week) but if allowed to dry out it would probably become at least semi-crunchy. When dry I don’t think it would bond tightly onto the slippery surface inside the tank, probably just fall off in chunks instead. Of course the sealed tank will never dry out on its own while being used semi regularly. One interesting tidbit though. We leave Michigan in January each year so after several below freezing days this year while packing up to go, I noticed the tank read empty! It was only temporary but apparently when frozen the goop is a lot less electrically conductive.

boiledowl · 10-05-2022, 05:46 AM

someplace on these forums someone posted that coachmen told him to put calgon bath beads in his tanks to clean sensors and he said it worked..

Brentw · 10-05-2022, 07:20 AM

Interesting, thanks for posting this. Kinda hoped Dawn would keep it clean, maybe I'll try some spray 9.

JNSNWT · 10-06-2022, 09:50 AM

Vibeman

This is mostly for black tanks but might be worth a try especially if you hook the power washer to a hot water source

https://youtu.be/2mGY63kgjh8

Old-Biscuit · 10-06-2022, 10:12 AM

Probes that protrude thru tank wall have always been unreliable due to coatings building up on the probes.
TP, soap scum, scale/calcium, etc

Hence the reason exterior sensors (circuit board) such as SeeLevel
*more reliable due to exterior installation BUT false readings can occur due to slime, etc on interior wall

I don't even bother with level monitors/sensors.
Toilet burps...time to dump black tank
Bathroom Sink/Shower starts draining slower....time to dump grey tank
Kitchen Sink starts draining slower.....time to dump galley tank
Water pump goes burrrrup....should have refilled fresh water tank

THenne1713 · 10-06-2022, 11:08 PM

There are commercial gray tank cleaner products, (I have not used); I think VINEGAR, but maybe wrong, and know that the PURPLE SPRAY (cannot recall brand name from TV ads?) was the closest/ best I could ever find for removing bath tub "SOAP SCUM" without vintage old abrasive cleaners? Some tout/ recommend DISHWASHER TABLETS and claim success, and a search engine will find you multiple brands online. IF you find something that works, I feel sure we ALL would love to see results from the borescope? :-) :-) e.g. https://search.yahoo.com/yhs/search?...ank+c%3Bleaner

Vibeman · 10-07-2022, 04:14 AM

Quote:

Originally Posted by boiledowl

someplace on these forums someone posted that coachmen told him to put calgon bath beads in his tanks to clean sensors and he said it worked..

On a trip last year i put a pint of Calgon Liquid Water Softener and a small bottle of Dawn dishwashing liquid in my tank (many people claim this works for them) and then drove a couple of days. i don't know what that combo might have done to the coating, but I do know it did NOT get the sensors to work.
After i tried several of these recommended "fixes" and none of them worked for me, i was beginning to think i might have some kind of a problem with my sensors, wiring, or Firefly readout. Before I drilled the new holes I got out my little red Harbor Freight multimeter and started measuring everything i could and compared it to the black tank sensors which were working correctly. Everything matched up EXCEPT the resistance measured between the 3 lower sensors when the wires were removed. Those measurements were different than on the black tank sensors. (it is now obvious why) Once I drilled the holes and cleaned the sensors all measurements were the same between the gray and black tanks and all sensors were reading correctly. Of course all readings and observations I have done so far are on EMPTY tanks. I also bought a little digital water meter on Amazon and I plan to use it to check the accuracy of the sensor placements in my 40 gallon tank as I fill it.

Vibeman · 10-07-2022, 04:22 AM

Quote:

Originally Posted by THenne1713

There are commercial gray tank cleaner products, (I have not used); I think VINEGAR, but maybe wrong, and know that the PURPLE SPRAY (cannot recall brand name from TV ads?) was the closest/ best I could ever find for removing bath tub "SOAP SCUM" without vintage old abrasive cleaners? Some tout/ recommend DISHWASHER TABLETS and claim success, and a search engine will find you multiple brands online. IF you find something that works, I feel sure we ALL would love to see results from the borescope? :-) :-) e.g. https://search.yahoo.com/yhs/search?...ank+c%3Bleaner

If I discover anything useful I will relay it here. At this point I am expecting the soft water to gradually reduce the existing coating. I will check it next summer. In the meantime I am also expecting the Horst sensors to work a lot more reliably than the original sensors.
Only time will tell.