Black water tank.

[Pete & Linda]

We have been camping for about 5 weeks. Some state parks and with no sewer and some parks with sewer. My MH has a black tank flush. I leave the valve closed until the tank is more than 3/4 full. I dump, flush and fill to over 1/2 full and dump again then more flushing and dumping. However when we dump at a dump station there is no flushing. Twice this trip after leaving where I was able to dump, flush ect and checking that the sensors are reading empty, when I get to the next CG and check the tank the 3/4 and full LEDs are on. Now I can't tell when the tank is 3/4 or full. I am where there is no hook up so this is a problem. Like I said I flush and fill and check the sensors and they read empty! Any ideas?

Thanks

[GENECOP]

Not exactly sure what you are asking, but inaccurate reading on the black tank sensor is common. Muck sticks to the tank sensor and renders them useless. Just get used to and track the time between dumps and dump accordingly. There are also aftermarket exterior sensors that work well, they mount on the outside of the tank and read levels, they hook into the same wiring for the int sensors, G

[wa8yxm]

Those stupid sensors are one of the first things to "Fail" on a motor home or trailer.. They usually work properly for one tank load, perhaps 2 if you are lucky.

There are two products that I find may help.. Both are black tank cleaning wands.

now understnad that most of the wands out there are a waste of money in my not very humble opinion.. I mean you could hold a hose over the toilet and do as good a job but these two are different.. I "home made" one of them

The first is, as I recall, called the RV-Twister... This one has a brass "Spinnner" on the end and as the water jets out of the spinner it blasts every bit of your sidewalls, You move it up and down a bit in the tank (I won't draw a parallel to that motion here) and with any luck blast every bit of the sensor wall clean.

The other is the Valterra Master Blaster.. I home made one of these by using a PVC pipe. hose fitting on top (I feed with dual backflow preventers) and cap the bottom.. Drill into the side of the cap, in line with the printed line on the pipe. using a drill of about 1/4 inch (mine was a bit smaller.. Happened to be what I grabbed first, 7/32 as I recall) and "Aim" toward the sensor wall

Again you move up and down, and twist slightly right and left (Unlike the twister this one you have to twist manually) and blast the wall clean.

Then till the next dump.. the sensors work

[Lt46]

Many have given up on relying on sensors. The tried and true is a flashlight and a peek through the toilet bowl.

[hamguy]

Quote:

Originally Posted by Pete & Linda We have been camping for about 5 weeks. Some state parks and with no sewer and some parks with sewer. My MH has a black tank flush. I leave the valve closed until the tank is more than 3/4 full. I dump, flush and fill to over 1/2 full and dump again then more flushing and dumping. However when we dump at a dump station there is no flushing. Twice this trip after leaving where I was able to dump, flush ect and checking that the sensors are reading empty, when I get to the next CG and check the tank the 3/4 and full LEDs are on. Now I can't tell when the tank is 3/4 or full. I am where there is no hook up so this is a problem. Like I said I flush and fill and check the sensors and they read empty! Any ideas? Thanks

My sensors have never read accurately but common sense tells me that immediately after dumping[flushing/dumping, the tank is empty. I also know that we can go a minimum of 5 days of normal useage without dumping. We can go 3days on the gray tank.

We dump every 3 days and have never had even a seconds worth of trouble.

[Pete & Linda]

Thanks everyone. What I don't understand is when I leave a campground after flushing ect. it is reading fine but then when we get to the next stop it's not. I guess the flash light will have to be it, the number of days will not always work as our grandson goes with up sometimes. I will try to find one of the flush things or make one.

[hamguy]

Quote:

Originally Posted by Pete & Linda Thanks everyone. What I don't understand is when I leave a campground after flushing ect. it is reading fine but then when we get to the next stop it's not. I guess the flash light will have to be it, the number of days will not always work as our grandson goes with up sometimes. I will try to find one of the flush things or make one.

Well, you can be assured that the amount in the tank didn't actually increase while travelling, can't you? And, I can use the flashligght to see directly down into the tank to see the level. And, if there is a question, DUMP. But, you should know the approximate useage.

[Cruzer]

Internal sensor are notorious for that. Go with a SeeLevel system from RVupgrades and you'll never have to deal with that again.

RVcruzer.com - SeeLevel Digital Tank Monitoring System Installation

[SwampTrash]

I've had this problem before, also. Dump and the indicator light shows empty. Go down the road and check and it shows 3/4 full. I just figured it was some water/muck left to slosh in the tank because after sitting a while the indicator light is correct again.

[Smathers]

Perhaps this video will help explain why you get false readings in your tank. It was an 'ah-ha' for me.:

YouTube - Horst Miracle Probes Demonstration

[TandW]

If you carry fresh water you can certainly flush at a dump only site. Side to side ground aspect at a dump station has a huge effect on clearing all solids. Have you ever opened a new can of paint and not found any paint on the underside of the lid. The same thing happens with a full black tank. In fact, until the waste tanks begin to fill to any appreciable amount, the top of the tank sags downward and will be in contact with floating solids, greases and oils long before they are full. Many flushing hydrants are worn out and do not open enough to provide full flow. Finally, this whole thing is a crap-shoot!! Good luck!!

[Ray,IN]

Many campers have found that the black tank will "burp" when it is nearing full, and you learn to listen for the change in sound of the falling water. I rarely even look at the rinky-dink light panel. I think what happens is, the sensors corrode quickly, and this corrosion holds moisture, which fools it into sensing it is the water level. When our RV sits unused for a week or more(with empty tanks) the sensors work fine, the moisture has evaporated.

[bdpreece]

Quote:

Originally Posted by Pete & Linda Thanks everyone. What I don't understand is when I leave a campground after flushing ect. it is reading fine but then when we get to the next stop it's not. I guess the flash light will have to be it, the number of days will not always work as our grandson goes with up sometimes. I will try to find one of the flush things or make one.

.0

The problem probably stems from the fact that the sensors are reacting to wet or dry debris giving different readings.

[Pete & Linda]

I think I was my own worse enemy. We stayed in a couple state parks and to stretch the tank we would flush with as little water as we could. So I think we sludged up the tank. I made a 4 1/2 day tank out of a 3 day thank. If I ever get it working I won't do that again!