Tank Sensors

[Pro BSer]

I am sure this topic has been asked a thousand times , but here goes
The 2012 Rushmore 35RL we purchased used just a little over a month ago but the holding tank gauges give very false readings.
I have flushed and flushed the black tank over and over using the flush line from the outside hoping that any tp stuck to the sensors might go away. I have tried the Dawn & Calgon thing so far the best I can get when empty the guage reads 1/4 and after only a few flushs down the toilet it shows full.
Any suggestions other than climbing inside the black water tank and hand scrubbing the tank down

[2slick]

Forget about it. Just dump when the toilet gurgles. This our third unit, all were the same.

[travelin texans]

X2 on forget them!! You'll drive yourself nuts trying to fix them & they might work once.

[Dayle1]

Same advise here, I haven't paid attention to the monitor in years. I just dump the black tank every two weeks and if I have time at least a single tank flush cycle. When I'm headed home I put in about 10 gallons and a 1/4 cup of Dawn dish soap so it can slosh around during the drive, then drain it as soon as I get home.

Only other option is to upgrade to an aftermarket system that uses external, capacitive coupling sensors like SeeLevel II.

[Pro BSer]

So it seems this is perfectly normal

[geondebi]

Sorry same here ... I have tried for years to get them to read correctly with no luck.

[Pro BSer]

Since the sensors are so notoriously unreliable, how do you really know when the black tank is full? I really don't like to empty the black tank unless necessary, in order to get a better flush.
I usually drain and flush after being out for a week unless needed more often.

[Dayle1]

Originally Posted by Pro BSer

Since the sensors are so notoriously unreliable, how do you really know when the black tank is full? I really don't like to empty the black tank unless necessary, in order to get a better flush.
I usually drain and flush after being out for a week unless needed more often.

In time you will figure out how quickly you are filling up the tank. And a better flush is not that critical if you can use the black tank flush immediately after dumping.

[Papa-T]

Same here. They never work accurate for long.

[SeanRN]

I've had brand new units that the sensors read full after the first use. It's kind of a losing battle. Although I will say since I bought my most recent unit, I have been using the Geo Method (laundry soap & calgon) and my sensors read empty when I dump the tanks. It may just be luck.

I'm really surprised that the laundry soap keeps the odors down. We use a lot of water anyway, and odors have not really been a problem, but the laundry soap seems like such a simple idea and much more environmentally friendly than holding tank products.

[Pro BSer]

I tried the Dawn + Calgon thing but all I could find was the lavender scented Calgon, guess that outta make the black tank poop smell pretty.

[Newb]

I tried all the suggestions from calgon to putting a bag of ice cubes in then driving down the road to get it to break free my tank has read wrong since I purchased it 4 years ago, finally i tried hot water. Just wait till you are about half full or more then fill the rest of your black water tank with hot hot water ( I just used my shower hand held unit ) then flush the system right away. It took me two times of doing this but now my sensors read correctly and actually read empty when I am done flushing the system.

[Pro BSer]

Thanks, I gotta try that!

[dedmiston]

If you use the ice method to break things up, make sure the weather is warm enough for the ice to break up. I've read many posts over the years where people added bags of ice to their black tank during the winter and were stuck with a frozen mess that wouldn't fit through the drain line.

[travelin texans]

In a 40-50 gal black tank a bag or 2 of ice is going to be pretty much useless. I've tried every remedy for curing the problem & some of them worked til the tank filled again, then false readings again. Now it's been probably 2+ years since I've even looked at them. The toilet makes a specific sound when you flush when it's time to drain, which is about 7-9 days, so typically drain every week.

[mark5w]

Even though it's a 40 gallon tank, the shape of the tank is a very low profile. Probably around 10 to 15 inches deep, so the ice should help out a little. I'd rather try the Geo method also and pouring in hot water is an idea I never thought of but should help.