Black tank/gray tank level indicators

inlyzbldcj · 06-15-2021, 07:15 AM

Ok, so we just came back from a trip this past weekend and since we had sewage at our site, I emptied the black tank, then the gray tank, and then flushed the black tank and hose out with the other hose hooked up to the city water system which our coach was hooked up to all weekend. Well, I get home and check the tanks and both the gray and black are showing 2/3 full....I KNOW those tanks emptied as I watched them empty into the sewage dump. Why are my tanks showing 2/3 full. I even went up to our dealers where you can dump tanks for free...attempted to dump them again, washed them out through the sani flush hook up and re-emptied them. I check the lights and still showing 2/3 full? Any ideas? Anyone ever run into this problem?

inlyzbldcj · 06-15-2021, 07:17 AM

Oh also....I filled up the fresh water tank before leaving and it shows empty even though we were hooked up to city water at the park and it was turned on....why would the fresh water tank empty if we were using city water?

Pete'sMH · 06-15-2021, 01:18 PM

Well unfortunately the gauges on many (most) RVs are wildly inaccurate. You might get them to work better by half filling your tanks with soapy water and driving around for a while in hopes of cleaning the sensors but it’s iffy and temporary at best. Most of us don’t really use the gauges and just sort of rely on experience to know when to dump. It’s pretty crazy but more or less true.

Beau388 · 06-15-2021, 01:38 PM

If you are worried about accurate tank levels, then I suggest you invert in the "Seelevel Tank Monitors".

Bob Denman · 06-15-2021, 02:08 PM

Those gauges lie enough to make a Politician blush...

The Gritz Carlton · 06-15-2021, 04:15 PM

What Pete said...in due time you will get that "gut feeling" they are full and need dumping. One day they may seem to work well and others not. Chew your food a little better and don't be afraid to run extra water in them while hooked up camping...dilution is your best friend. As he also said...if you know you're heading to another campground with hookups the next night, fill them half way and add soapy something. The sloshing around as your drive will help wash the corn and toilet tissue off the sensors. It's dumbfounding how all that corn we eat and chew up so well seems to always make it back into every single kernel before we pass it.

Trophy1200 · 06-15-2021, 07:07 PM

Quote:

Originally Posted by The Gritz Carlton

It's dumbfounding how all that corn we eat and chew up so well seems to always make it back into every single kernel before we pass it.

That’s why I don’t eat corn, don’t see the point in eating something that comes out exactly the same as it went in.

Bob Denman · 06-15-2021, 07:17 PM

Quote:

Originally Posted by Trophy1200

That’s why I don’t eat corn, don’t see the point in eating something that comes out exactly the same as it went in.

https://www.thorforums.com/forums/at...1&d=1623784635

Campnjoe · 06-15-2021, 09:40 PM

Quote:

Originally Posted by inlyzbldcj

Ok, so we just came back from a trip this past weekend and since we had sewage at our site, I emptied the black tank, then the gray tank, and then flushed the black tank and hose out with the other hose hooked up to the city water system which our coach was hooked up to all weekend. Well, I get home and check the tanks and both the gray and black are showing 2/3 full....I KNOW those tanks emptied as I watched them empty into the sewage dump. Why are my tanks showing 2/3 full. I even went up to our dealers where you can dump tanks for free...attempted to dump them again, washed them out through the sani flush hook up and re-emptied them. I check the lights and still showing 2/3 full? Any ideas? Anyone ever run into this problem?

What coach do you have? Some seem to work better than others.

Badmanrick · 06-15-2021, 10:04 PM

I had a Bullet Premier travel trailer and had the same problem. It had the button tank sensors in all tanks, black, gray, & Fresh. Skum collects on the side of the tanks and shorts out the sensors so they show incorrect readings.
These sensors are the cheapest sensors that the factory can install.
I changed all mine with the Horst extended sensors from Valtera. They worked a lot better.
When I upgraded to our new 2019 Thor Hurricane34j I immediately change the sensors out.
The black tank sensors must be installed with the opening facing down. The gray/fresh sensors do not have a cover but stick about 3” inches into the tank like the black sensors.
There are other very expensive alternatives which you can check out on you tube.
I purchased mine from Amazon

Pete'sMH · 06-16-2021, 12:27 AM

It’s all sort of mysterious. My tanks have external sensors and even still they frequently are inaccurate. Other times they seem to work pretty well.

Bob Denman · 06-16-2021, 12:40 AM

Mine too... and you're right: they do like to keep things "interesting",..

Campnjoe · 06-16-2021, 02:54 AM

Quote:

Originally Posted by Badmanrick

I changed all mine with the Horst extended sensors from Valtera. They worked a lot better.
When I upgraded to our new 2019 Thor Hurricane34j I immediately change the sensors out.
The black tank sensors must be installed with the opening facing down. The gray/fresh sensors do not have a cover but stick about 3” inches into the tank like the black sensors.
There are other very expensive alternatives which you can check out on you tube.
I purchased mine from Amazon

This is really interesting. I will have to check these out as the seelevels wont work with our firefly system.
How was the install?

Badmanrick · 06-16-2021, 11:30 AM

Install was very easy. Just drill a new hole next to the existing tank sensors and move the wire over. It will work with the firefly system.

Grumpy Grampa · 06-17-2021, 01:30 AM

Simple, disconnect the battery, let it sit 10 minutes reconnect, See if the sensors reset.

Lockpro · 06-19-2021, 06:16 PM

Quote:

Originally Posted by inlyzbldcj

Oh also....I filled up the fresh water tank before leaving and it shows empty even though we were hooked up to city water at the park and it was turned on....why would the fresh water tank empty if we were using city water?

On my coach, the city water is one connection and the fresh water fill is another connection. The city water is a pressurized connection and you have to tighten the hose so it doesn’t leak. It bypasses the coach water pump which is not needed due to the city water pressure.

My water tank fill is another “connection”, actually just a pipe with a cap, and you put a hose in it and fill until water runs out. (I actually use a gallon meter and stop it 5 gallons short of full because I have a leak)

So on my coach, being connected to city water does not fill the fresh water tank. Your mileage may vary.

dsknoop · 06-19-2021, 06:28 PM

Tank gauges are not reliable. Mine constantly show 2/3 to full right after complete dumping, flushing, cleaning. You will learn from experience how long you can go without a problem. ie: I have a 30’ Thor Chateau (class C) and I’ve done fine boondocking for 9 days. 3 days of that was with 3 adults in the RV. Learn to conserve your water usage. Only put TP used for BM down the toilet. All other TP goes in the trash.

NG7V · 06-19-2021, 06:43 PM

We do lots of camping in the southwest where the water contains lots of minerals. Over time, there is a coating in the black tank called struvite. That coating can be very thin or very thick depending on how long the tank has been in use in that environment. There are two ways to get the struvite out of your tank(s): Get a service to come and clean/inspect the inside of your tanks or, use a probiotic chemical to break down struvite and wast but that can take a lot of time.

I call the TankTechs in once a year to clean my tanks out and, this year was the first year I use probiotics on my tanks. They stay cleaner that before but still need work to get rid of all the crud.

Look up Welcome to TankTechs where we solve holding tank problems, GUARANTEED! if you have an interest in what this is all about.

Slmangels · 06-19-2021, 06:59 PM

Quote:

Originally Posted by inlyzbldcj

Oh also....I filled up the fresh water tank before leaving and it shows empty even though we were hooked up to city water at the park and it was turned on....why would the fresh water tank empty if we were using city water?

The gauges really never seem accurate. Don’t worry about. The gauge might have some paper hung up on it.

Paperboy · 06-19-2021, 07:49 PM

I presume you're camping with black tank closed, and flushing at 2/3 or so. 1) use a clear elbow at the end of the hose to see what's going down. It can happen that the volume moves enough solids to plug the hose, but this usually flows after a bit, although you may think it's finished. Shake the hose. 2) get a "black tank sensor wand" and bring it in a window attached to park water. Step on the toilet handle and flush up and down and twist it. Mimics what they factory install to clean off the sensors. Add fresh water and flush again. Should run clear. Repeat till you get tired or sensors read zero!

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