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Black holding tank censors

ejd43
Explorer
Explorer
Does anyone out there have any tips to help my black tank censors read more accurate? I can empty it out totally and the gauge still reads that it's full. Its driving me nuts that I dont have an accurate read, and makes it difficult to gauge when it's full.
30 REPLIES 30

2012Coleman
Explorer
Explorer
The best black tank sensors are your eyes, looking down the hole while flushing with the assistance of a flashlight.
Experience without good judgment is worthless; good judgment without experience is still good judgment!

2018 RAM 3500 Big Horn CTD
2018 Grand Design Reflection 303RLS

Mark_and_Linda
Explorer
Explorer
We use a dishpan to wash the dishes every now and then. I will take that pan of soapy water and dump it into the commode. Sometimes if I think about it, I dump the ice from the trays into the commode....let them beat around while I am going to the dump. I check mine every now and then...but use the method mentioned earlier...look down the flapper.
Mark

bartlettj
Explorer
Explorer
Mine still work fine after 7 years of ownership. Every few dumps I fill the tank 3/4 with clean water, and take it for a drive, then dump it. That, combined with using plenty of water, Kirkland toilet paper, and Happy Camper, no issues with the sensors after cleaning. Sometimes I'll throw in 10 lbs of ice cubes before the drive to really break up any crud.

Ride_S40T
Explorer
Explorer
After about 6 camping trips in the new RV the black started to read 1/3 even when completely empty.

1. We probably weren't using enough water when we flush.
2. We were probably using too much anti-smelly stuff...again with not enough water.
3. Poured 5 gallons of really hot water in there and think we added vinegar. Drove it around town on bumpy roads with several turns (10-15 min), drained. No issues since.
2021 Grand Design 268BH
2019 GMC Sierra Denali HD 3500 SRW
Traveling K9s Diesel and Roger

drsteve
Explorer
Explorer
Tank chemicals are only useful for converting your money into someone else's money. It's not a septic tank, it's a holding tank. Waste isn't in there long enough to break down.
2006 Silverado 1500HD Crew Cab 2WD 6.0L 3.73 8600 GVWR
2018 Coachmen Catalina Legacy Edition 223RBS
1991 Palomino Filly PUP

pbeverly
Explorer III
Explorer III
My sensor was doing the same thing. I use Tank Busters. It is less than $10 for four packs. Filled tanks with it it, let it set overnight, drain, filled again, drained, sensor good again. I do this with grey, black and portable tank. Waste of money? Nah, 4 treatments for less than $10, worth it if it works.
Ridgeway, SC
2019 26DBH Grey Wolf

RICK-ards_Red
Explorer
Explorer
DutchmenSport wrote:
Same as MFL here. Dump your tanks, add a few gallons of water. Add some Dawn Dishwashing Liquid or Laundry Detergent, travel to your next destination. If you do this every time you travel, sensors will work.

Do this in combination with your black tank flusher, backflushing from your grey tank, and even use the toilet wand on the end of a garden hose occasionally, all this will help keep your tank clean and sensors responding better.


That is a good idea with the soap - thanks
2017 Coachman Catalina 25RKS
2015 GMC Sierra 1500 - Kodiak edition

mosseater
Explorer
Explorer
double tap
"It`s not important that you know all the answers, it`s only important to know where to get all the answers" Arone Kleamyck
"...An unarmed man can only flee from evil, and evil is not overcome by fleeing from it." Col. Jeff Cooper
Sunset Creek 298 BH

mosseater
Explorer
Explorer
I haven't looked at my sensors in about 8 years. After a while you just know.
"It`s not important that you know all the answers, it`s only important to know where to get all the answers" Arone Kleamyck
"...An unarmed man can only flee from evil, and evil is not overcome by fleeing from it." Col. Jeff Cooper
Sunset Creek 298 BH

Hannibal
Explorer
Explorer
We use a lot of water with flushes. Works like a champ. Ours has a black tank flush but it seems more of a gimmick than a useful feature.
2020 F250 STX CC SB 7.3L 10spd 3.55 4x4
2010 F250 XLT CC SB 5.4L 5spdTS 3.73
ex '95 Cummins,'98 12v Cummins,'01.5 Cummins,'03 Cummins; '05 Hemi
2017 Jayco 28RLS TT 32.5'

mbopp
Explorer
Explorer
Happy Camper tank treatment and a toilet wand kept my black tank sensors working on 3 trailers.
2017 Grand Design Imagine 2650RK
2019 F250 XLT Supercab
Just DW & me......

Lynnmor
Explorer
Explorer
Those "sensors" are merely bolts thru the side of the tank, not some fancy electronic device. They do not need to be clean, the problem is the scum on the tank wall bridges the space between the bolts and allows current to flow. The system works by applying voltage to the bottom bolt and water completes the circuit. The more bolts reached by water, the higher the gauge reading. Keeping the tank wall clean will allow the gauge to work properly, but that is nearly impossible. If you use chemicals, soaps, detergents, water softeners or anything else, remember that they will increase current flow so the tank needs thorough rinsing with clean water after use, just like washing anything else.

time2roll
Explorer II
Explorer II
I use a Quckie-Flush with a custom spray pattern to direct water at the sensors. Also to direct more water to the side of the tank opposite of the drain. The 'junk' oem sensors still work perfect after 14 years.

opnspaces
Navigator
Navigator
There was a guy who did a video series testing black tank emptying and cleaning solutions. you might find some of them interesting.

Original test

Much longer but worth at least the first 8 minutes
Adding ice cubes to black tank
Testing mounting height of tanks
.
2001 Suburban 4x4. 6.0L, 4.10 3/4 ton **** 2005 Jayco Jay Flight 27BH **** 1986 Coleman Columbia Popup