black tank is 2/3 full but it is empty

[Stan]

i have a 2018 reflection 315 RLTS and I’m working on resolving some issues before winter. The panel indicates 3 lights (2/3 full) but the tank is empty. I hooked up my wand to the water house and cleaned out the tank again through the stool. I filled the tank up nearly full twice in hopes of cleaning it out really good and then completely drained it but with no luck as it still reads 2/3 full. Thoughts!

[TucsonJim]

I have owned five different RV's over the last 30 years and none of them had an accurate holding tank measuring system. I did a very thorough cleaning of my black tank a couple of weeks ago, and it's been parked since then. I just checked, and it's still showing 2/3. These gauges are notorious for being inaccurate.

I know my black tank is near full when I start to see air come up through the toilet while flushing. That means that the fluid level is equal to the vent pipe and it's time to dump.

One method for obtaining accurate readings is to install an aftermarket product called See Level Gauges from Garnet Instruments I'm attaching a link below:

garnetinstruments.com/rv-shop/

[Yoda]

While this may not help you now, I have had very good luck with adding Dawn dish soap (1 cup) to my black tank with 5 gallons of water to charge the system after dumping. Hopefully the the next time you dump the sloshing with the Dawn will have broken up any tissue or solids on the tank level contacts. Folks will say any dish soap works, but I have had the best luck with Dawn. It also cuts the order. In addition some folks say they have luck with a few tabs of washing machine detergent (Tide I believe).

You could try the Dawn and fill tank 3/4 full then get inside the rock the trailer, let it sit for a while, rock the trailer again and dump. You never know.

Hope this helps
Keith

[Andi]

While this may not help you now, I have had very good luck with adding Dawn dish soap (1 cup) to my black tank with 5 gallons of water to charge the system after dumping. Hopefully the the next time you dump the sloshing with the Dawn will have broken up any tissue or solids on the tank level contacts. Folks will say any dish soap works, but I have had the best luck with Dawn. It also cuts the order. In addition some folks say they have luck with a few tabs of washing machine detergent (Tide I believe).

You could try the Dawn and fill tank 3/4 full then get inside the rock the trailer, let it sit for a while, rock the trailer again and dump. You never know.

Hope this helps
Keith

We've started doing this as well. After dumping, add a few gallons of water, the Dawn dish liquid as well as some Calgon water softener (found in laundry aisle, not the stuff you take a bath in). Our gauge was reading 2/3 full even when empty. After driving home with this concoction in the tank, when we dumped to winterize, the gauge now reads empty.

[howson]

i have a 2018 reflection 315 RLTS and I’m working on resolving some issues before winter. The panel indicates 3 lights (2/3 full) but the tank is empty. I hooked up my wand to the water house and cleaned out the tank again through the stool. I filled the tank up nearly full twice in hopes of cleaning it out really good and then completely drained it but with no luck as it still reads 2/3 full. Thoughts!

I don't bother looking at the indicators, either. As Jim (@TucsonJim) stated, the indicators are notoriously inaccurate. I flush my tanks on a regular basis when I'm camping.

As Keith (@Yoda) suggested in his post, there's a "Geo Method" that my wife and I use while traveling (google it). Immediately after flushing the tanks she adds the concoction and we've had no issues with clogging, smell, etc.

[Stan]

I took the camper to have it worked on. Regarding the incorrect reading on the black tank he said to simply put a bag of ice down the stool with a little water and then go for a drive and the ice will clean the sensors off so it will give you an active reading! Interesting idea!!

[howson]

I took the camper to have it worked on. Regarding the incorrect reading on the black tank he said to simply put a bag of ice down the stool with a little water and then go for a drive and the ice will clean the sensors off so it will give you an active reading! Interesting idea!!

That's in the same thought process as the "Geo Method"--clean off the sensors. The benefit of the Geo is the Dawn soap actually cleans the tank as it sloshes around in the tank.

You'll eventually know when it is time to dump without looking at the sensors, but keeping the tank clean is still good preventative maintenance IMO.

Also--moved this thread to the Plumbing channel.

[JeffC]

I took the camper to have it worked on. Regarding the incorrect reading on the black tank he said to simply put a bag of ice down the stool with a little water and then go for a drive and the ice will clean the sensors off so it will give you an active reading! Interesting idea!!

There is a really good video on YouTube where a guy builds a tank out of clear plexiglass, puts in some "NASA poop" and tries the ice cube method while driving around town. No workee.

[Second Chance]

There is a really good video on YouTube where a guy builds a tank out of clear plexiglass, puts in some "NASA poop" and tries the ice cube method while driving around town. No workee.

https://www.youtube.com/watch?v=iH6acEmqvcw&t=356s

And the ice thing only works in cold weather. In warmer weather, it melts to quickly to accomplish anything.

Rob

[RVKevin]

I realize this thread is old, but we just bought a 315RLTS (2021) too. Same problem with the black tank. I can get it to read empty, but as soon as I add ANY water, it shows 2/3 full. Then it stays at 2/3’s full until I dump it. After 3 fill/dump flushes with clean water, I can again get the tank indicator to say empty. But adding anything to it shifts it to 2/3’s full. And I can still see the bottom of the tank through the toilet!

The thing that frustrates me is that Airstream seems to have figured this out. We owned an Airstream for 5 years before buying this Grand Design (needed more space—those Silver Bullets are really tiny when you add 2 cats and their litter box!) and are very happy with the 315RLTS, EXCEPT for this tank issue. I would have thought that it’s something easily resolved, especially given that Airstream has figured this out.

[Cate&Rob]

RVKevin
Welcome to our owners technical forum.

As mentioned earlier in this thread and discussed at length in several similar threads, the tank level gauges (particularly the black tank) are notorious for being inaccurate. The OE button probes are easily "connected" electrically to wet debris on the tank side wall with the least bit of contamination. There are better quality shielded probes (maybe your previous trailer had these?) The probes can be changed out for the better quality ones with no wiring or other changes, but (particularly if you can see into the tank) is this worth dropping the underbelly to accomplish this? Many of us just ignore the level gauges . . . I know that I do. Pressing that button to get a reading that is very likely incorrect is not good for my blood pressure .

Rob

[howson]

I realize this thread is old, but we just bought a 315RLTS (2021) too. Same problem with the black tank. I can get it to read empty, but as soon as I add ANY water, it shows 2/3 full. Then it stays at 2/3’s full until I dump it. After 3 fill/dump flushes with clean water, I can again get the tank indicator to say empty. But adding anything to it shifts it to 2/3’s full. And I can still see the bottom of the tank through the toilet!

The thing that frustrates me is that Airstream seems to have figured this out. We owned an Airstream for 5 years before buying this Grand Design (needed more space—those Silver Bullets are really tiny when you add 2 cats and their litter box!) and are very happy with the 315RLTS, EXCEPT for this tank issue. I would have thought that it’s something easily resolved, especially given that Airstream has figured this out.

Welcome to GD's Owners Forum (from a fellow 315RLTS owner). As that was your first post (don't worry about adding on to an old thread--that fine) please check out the Welcome Letter to New Members https://gdrvowners.com/forum/main-fo...to-new-members

This may not be good news, but the sensors on the tanks in our trailer are worthless. I haven't bothered to monitor the system with the lights after I figured out how inaccurate the sensors are.

The picture below shows a fresh water tank without sensors installed. (The sensors work the same way on every tank; fresh, gray, or black.) I'm not 100% how the sensors interact with the display panel, so I'll defer to others who have more knowledge on this system to explain.

Can you also tell me if your trailer is CompassConnect enabled? If so, what does the control panel look like? Please take a pic and post it.

[Country Campers]

RVKevin

If this issue has been the same since new it is possible that the probes are wired wrong , just a thought.

Brian

[Guest]

So far I've been lucky with the approximations of the level indicator but then again, after draining and using the tank flush at the dumping station, I flush the heck out of the black tank with the tank flush again when we're home. I flush the system into 5 gallon buckets and pour them down the toilet in the house.
While camping, turning the water off and simply looking down the toilet opening with a flashlight will tell you how far you have to go. Also we know from experience how many days we can dry camp with grey, black and water tanks. But I still check.

Also to add: After flushing, I add water and prep for the next trip while keeping the system wet. To have some contents dry out in the tank may explain why the indicators remain fowled.

Jim

[howson]

RVKevin -- I found out the 2021 315's tank sensors are wired to the control panel just like my '19. The CompassConnect system is your unit is not utilized for tank levels.

What Country Campers (Brian) wrote is also my suspicion. You might consider having the dealer verify the wiring if you bring the unit in for other service. If this is something you want to pursue yourself, holler back.