Cleaning Black Water Tank Sensor

Oregonbound · 10-22-2013, 12:03 AM

Hi all. Loving the RV lifestyle in our 36FL. Close on our house tomorrow so guess we're pretty committed at this point.

Our black water tank sensor has not worked properly since the purchase (always shows 2/3 full). I have tried several times traveling with the tank partially full with cleaner and it works for a couple of days then back to same. I am thinking of trying the Camco Swivel Stik but I'm not sure if the black tank is directly below the toilet or if it is offset - in which case I'll need the Flexible Swivel Stik. Does anyone know this?

Also, any pos/neg experiences with the Swivel Stik or other method for getting the sensor to work properly would be appreciated. Thanks

Adamsvr · 10-22-2013, 07:45 AM

Empty your black tank and pour ten pounds of ice down your toilet before moving to the next campground. Once at the campground, and connected to a sewer, connect your water hose to the sewer flush connection in your garage convenience center, turn on the water for five minutes. Turn off the water and open your black tank. You should be good to go.

Water is your friend to keeping your sensors clean. When flushing, when you no longer see debris coming through, keep the water flowing for another 15 minutes.Edited by: Adamsvr

johnboytoo · 10-22-2013, 08:59 AM

Like adamsvr said - ice someties does it, but if it's one of the 'higher' sensors, you may have to fill up TO that 2/3 height to slosh away the 'hanger'...
Wondering - do you usually leave the black tank drain open all the time when connected to sewer ?

One thing I've found is that I leave all drain valves closed until full (or ready to dump), then and only then dump black first, then grey...

More volume = better flush and less likely of sensor issues...

When I first starting this rv thingy, I had a sensor 'hanger' and filled the tank up and dumped calgon beads in there while towing to the next spot... that fixed it...

Also, after dumping I usually leave a few gallons of water in the black tank... so much for poop 101

Edited by: johnboytoo

Oregonbound · 10-22-2013, 09:01 AM

Thanks Adamsvr. Had not heard of that method so will give it a shot. Any idea as to whether the black tank is directly below the tiolet or off to the side? Also, whether the sensor is internal or sits on the outside of the tank? Thanks again.

Oregonbound · 10-22-2013, 09:09 AM

Thanks Johnboytoo. I think when we were real newbees earlier this summer, we did leave the black tank open on occassion and that does correspond to when we started having issues. We do now leave the valve closed till full, release it, then use the tank flush till clear. Will try to flush for longer as you, the Calgon beads and leaving some water in the tank for travel (we haven't consistently done that). Out of curiousity, do the Calgon beads work mechanically or do they have a chemical/cleaning efect. Maybe a combination of ice and the calgon beads would be a sure thing

Adamsvr · 10-22-2013, 09:27 AM

Quote:

Originally Posted by Oregonbound

Thanks Adamsvr. Had not heard of that method so will give it a shot. Any idea as to whether the black tank is directly below the tiolet or off to the side? Also, whether the sensor is internal or sits on the outside of the tank? Thanks again.

The black tank is more or less directly below the toilet. The sensors are drilled through the outside of the tanks and protrude into the tank.They look like they are made of brass and have one ground wire connected to them. When water levels reach each sensor, the circuit is closed and the appropriate light is illuminated. What normally happens is toilet paper hangs on one of the sensors and closes the circuit prematurely. That's why it's important that you use quick dissolving TP designed for RV's/Boats. We use Scott's available in Walmart RV section.

Adamsvr · 10-22-2013, 09:35 AM

Also, when you leave the black tank open, sewage builds up like a mountain at the bottom of the tank and then hardens, where water can no longer flush it away. That's why you important to close your black tank valve after flushing so liquids keep things soft until you flush.

We do normally keep our Galley and Grey tanks open when at a campground. Hope that helps.

Oregonbound · 10-22-2013, 10:22 AM

It helps

Thanks. Think I may try the Flexible Swivel Stik to see if I can clean the sensors.

Oregonbound · 10-22-2013, 10:24 AM

Besides Calgon, has anyone used any other chemical treatments such as Drano, etc.?

Adamsvr · 10-22-2013, 10:34 AM

Don't use Drano! It's too corrosive and can eat the rubber seals on your valves.

I have used Pine-Sol, but it really didn't do the job.

KenM · 10-22-2013, 10:41 AM

There are several products out there that are made for cleaning the sensors including Thetford 24545 Level Gauge Cleaner. I have used the product in the past and it works well. You can also put several bag of ice in the tank and drive around with the coach and the moment with the ice will also clean the sensors and the tank.

johnboytoo · 10-22-2013, 01:48 PM

The calgon beads and ice would be a good mixture...
the ice 'crashes' against the side until melted and the calgon makes it 'slippery-er' ?!?

obviously wait until the last minute before you drive to put ice in so it has time to work before melting - Dooh

the issue is to get the level to the correct height to clean THAT sensor off...

I had to guess the first time and it didn't help, the put a bit more the next time and that did it...

we also close our grey tanks the night before we are going to dump black to give us soem pre-cleaning after dumping black...

Edited by: johnboytoo

Willranless · 10-22-2013, 02:19 PM

Here is a link to a site with information about cleaning the tanks also.

https://sites.google.com/site/cbruni/

rcflame · 10-22-2013, 09:08 PM

I have tried several different methods of trying to keep the sensors clean, and the only way I have found that will keep them clean all the time is to put the system in that has the sensors on the outside of the tank. I have used the commercial tank sensor cleaner, the water softener method, a concoction I was told about which was equal parts ammonia, pine sol, and downy fabric softener. The ammonia etc. mixture seems to work best for me, but it is temporary even though I flush the black well every time I dump. It works best if I put it in with some water just before I go down the road. I have a sea level gauge setup that I am going to put on when I have the chance, but it is going to take a little time. I had this setup on one of my other rv's and it works great. It reads the tank level through a circuit board that sticks to the outside of the tank. It reads in percentage of full instead of 1/3, 2/3 etc. Maybe this winter I will have a chance to drop the belly and get it installed.

Oregonbound · 10-22-2013, 10:59 PM

Quote:

Originally Posted by johnboytoo

The calgon beads and ice would be a good mixture...
the ice 'crashes' against the side until melted and the calgon makes it 'slippery-er' ?!?

obviously wait until the last minute before you drive to put ice in so it has time to work before melting - Dooh

the issue is to get the level to the correct height to clean THAT sensor off...

I had to guess the first time and it didn't help, the put a bit more the next time and that did it...

we also close our grey tanks the night before we are going to dump black to give us soem pre-cleaning after dumping black...

Good Point about the level of the ice being important. Would not have thought of that!

Oregonbound · 10-22-2013, 11:09 PM

I bought a "Bonaire Soap Dispensing Wash Spray Gun" today at WalMart. It has a spray head that you can adjust for angle (0-100 degrees or so). I added a Pine-Sol-like product to the dispenser and sprayed down the tank from the toilet (the Black tank is indeed directly below the toilet). Saw some toilet paper wash out and sure enough, after cleaning and draining x2 the tank gauge shows empty for the first time that I can remember.

I will definitely keep the black tank closed from now on and will try the ice next time if it happens again. As the internal sensors seem destined to catch things, will also look into getting external sensors as mentioned at some point.

Thanks again for everyone's input/help....much appreciated. Great forum with great folks

johnboytoo · 10-23-2013, 07:22 AM

You shouldn't need the external sensors once you get your regimen down pat....

Have only had the sensor issue once and that's one of the lessons you NEVER forget

Oregonbound · 10-23-2013, 08:49 AM

Quote:

Originally Posted by johnboytoo

You shouldn't need the external sensors once you get your regimen down pat....

Have only had the sensor issue once and that's one of the lessons you NEVER forget

Good to hear it may be fixed permanently. Would only consider the time/energy for an external sensor if I'm consistently looking down "the hole". Thanks Johnboytoo

5th_Time · 10-23-2013, 11:03 AM

FYI, the sensor is located on theendof the tank a few inches from the discharge valve (RL). You can view it by taking down the belly pan on the street side. Each tank has four sensors: EMPTY, 1/3, 2/3, FULL. Different color wires for each. Grey and Black tanks havesame configuration.

Mine always read 2/3. Turns out, they had the wires from the monitor panel to the sensor mixed up.Edited by: 5th_Time

rcflame · 10-23-2013, 09:35 PM

If you come up with a system that will keep your sensors clean all the time, let me know. We use our tanks 24/7/365. We get ours clean and they're somewhat accurate for a few dumps, and then you can't trust them again. The sensors are basically carriage bolts with wires attached. I can live with it, because I know about how long it takes to fill them up. It just bugs me. I guess the sea level gauges I had kind of spoiled me. Hopefully I will get them on this summer.

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