Gray and black tanks do not completely empty

[RobinA]

We had to using the dumping station at the state park we stayed at last week. After going through the process to empty our tanks they still registered as 1/3 full. Any ideas on what we may have missed? We never had this issued with our bumper pull so not sure if we need to do something different.

[Grumpy]

Could just be bad guages. Sometimes residual moisture will also give a false reading.

[dalebra]

This has been a common issue for me when using a dump station and not having the ability to rinse the tanks good. Something is most likely hung up on a sensor inside the tank to give you a false reading. Before leaving for your next trip put 5 to 10 gallons of water in each tank. Then as you travel this water will slosh around in your tank and hopefully clean your sensors off. When you get to your next destination and hopefully have a sewer connection dump your tanks again and check your gauge.

[TWP723]

It's possible you have debris on one of the sensors causing a bad reading. It happens a lot. A good solution is to get one of those "wands" you stick in the tank that cleans the walls and sensors. Your tanks are most likely empty, especially if you remove the cap and nothing flows out. Make sure the gates are opening and you don't have a faulty waste valve. Other than that, probably debris.

[rkresge]

Originally Posted by RobinA

We had to using the dumping station at the state park we stayed at last week. After going through the process to empty our tanks they still registered as 1/3 full. Any ideas on what we may have missed? We never had this issued with our bumper pull so not sure if we need to do something different.

We had a bit of a challenge with our 'old' TT, a SLX 165RB, where the black sensor always read "full", so I finally got one of those wands for flushing out the tank. Worked great. Must have been some debris on the sensor. Luckily our new Jay Feather 23RLSW has a black water flush system.
On the grey water issue, I noticed in the 165RB that it would go from empty to 1/3 really fast. Didn't worry too much about it, as long as I was confident that I was getting it drained as much as possible. Is a dump station that much different from a regular hookup? I wouldn't think so, unless you want to get it done in a hurry and don't wait for it to completely drain. No experience.

Roger

[dalebra]

Originally Posted by rkresge

Is a dump station that much different from a regular hookup? I wouldn't think so, unless you want to get it done in a hurry and don't wait for it to completely drain. No experience.

Roger

Usually the issue and difference using a dump station vs. a site with a sewer hook up is the time needed and the availability of fresh water for rinsing. My experience with using a dump station is you may have others waiting in line so you don't have the time even if you had water on board to rinse. The other is most don't have a hose connection for fresh water because of the contamination possibility.
I don't worry about it during the season, using a dump station but I make sure at the end of the season on my last trip, that I have a sewer connection so I can fill and dump tanks several times before storing for the winter.

[dalebra]

One other point that I'm sure has been mentioned many times is to purchase a clear 45 degree sewer connector and use it right on the connection to the dump outlet and then attach your sewer line to it. With this clear piece you can then see when your tanks are clean. I always run water and flush until everything runs clear. By doing this I have never had a stinky TT.

[oldmanAZ]

x2 all of the things said previously regarding the black tank:
- I have a clear connector
- use the built-in black tank flush
- flush until the water runs clear
- add water into to black tank after flushing.
(BTW, adding water is important to not build a 'tower of poo' at the bottom of the tank.)

I must have debris stuck on a sensor because it always shows 1/3 full even when it is totally empty. I never used any chemicals (never had an odor problem), but next season I will use chemicals (before the 'wand') to see if I can get that sensor clean.

[tularockstar]

You may want to also consider testing a few brands of toilet paper as well. From our experience, cheaper brand of paper did not dissolve/breakdown very well in the tank. Thus, it gets clumpy and then creates havoc by covering the tank sensor. We found that the Scott's brand has been the best so far for us. It dissolved very well and we haven't encountered any tank sensor issue yet. The use of the black tank rinse connection is also key to a cleaner tank.

Happy camping!

Originally Posted by RobinA

We had to using the dumping station at the state park we stayed at last week. After going through the process to empty our tanks they still registered as 1/3 full. Any ideas on what we may have missed? We never had this issued with our bumper pull so not sure if we need to do something different.

[RobinA]

Thanks for all the info everyone!!

[goducks]

Are you using the black tank flush?

[Cdash]

Originally Posted by oldmanAZ

x2 all of the things said previously regarding the black tank:
- I have a clear connector
- use the built-in black tank flush
- flush until the water runs clear
- add water into to black tank after flushing.
(BTW, adding water is important to not build a 'tower of poo' at the bottom of the tank.)

I must have debris stuck on a sensor because it always shows 1/3 full even when it is totally empty. I never used any chemicals (never had an odor problem), but next season I will use chemicals (before the 'wand') to see if I can get that sensor clean.

I've given up on tank sensors. I just wing it. Have a pretty good idea of how long we can go without worrying.

I always heard that a combination of Calgon powder (like 1 cup) and 1 cup of laundry detergent and about 10 to 15 gallons of water in a tank to clean it. Never used it on my gray tanks, but did it all the time on my black tank. Would always release stuff that the black tank sprayer missed. I used chemicals in my tank only once: to get rid of the bottle they have me at delivery.

[Robbbyr]

As the owner of 3 different MHs over the years my observation is that the issues with gray and black tanks crossover to all types of RVs. Like anyone who has had tanks for years, I also have had my share of issues ranging from odors to inoperable level sensors. After considerable research and some trial and error I have a system that works well for me.

After a trip where I likely won't be back on the road for several weeks I empty and use the installed black tank flush until it runs clear. Then I close valves and add a solution of Savogran TSP powdered cleaner, liquid Calgon water softener, and warm water to the tanks. More solution obviously into the black tank. Then I go for about a half-hour to 45 minute drive on my good Ohio back roads taking many turns and making many starts and stops. Then I dump and flush again and I am amazed every time on what else comes out of both tanks! It must be grease and soap scum in the gray tank and make your own guess about the black tank. Never had any more problems with the level sensors or any storage odors.

TSP available at your local big box home improvement store and the Calgon is at Walmart in the laundry aisle.

[F14man]

you can get a clear drain hose attachment and you can get if your done draining.

[Jagiven]

When my sensors start to act up. After dumping, I add 5 plus gallons of water and a cup of liquid fabric softener to each tank. Drive home with it sloshing, and then drive to the next CG. Typically after two trips doing this my sensors read good again. My htt tanks are small, so you might need 10 to 15 gallons in you rig.

Both do the same thing, just differently. Water softener is probably cheaper.

One more thing alway keep a few gallons of water in each tank, this will help keep debris from drying on the sensors, and keeps the from being stinky.

[TCNashville]

Originally Posted by RobinA

Thanks for all the info everyone!!

Take a look at this. I'm going to do this 3-4 times a year. The GEO Method.

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

[gaserv]

Originally Posted by TCNASHVILLE

Take a look at this. I'm going to do this 3-4 times a year. The GEO Method.

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

Good info, Thx

[BigJohnD]

Geo Method for us too, kind of. I make my own home brews. It's a turd tank, so not much will hurt it, as long as you're careful with chemicals and make sure nothing will hurt the valve seals. Lots of things will work. If you ever continue to have sensor problems, try Unique RV Digestit. You can use it for a regular tank chemical, but more importantly, you can use it to clean EVERYTHING out of the tank. It has directions for both. I haven't had to use it as the cleaner on mine, but have on other peoples rigs, and several years worth of stuff came out. The stuff works. Put the bottle of stuff in, fill tank up past the full sensor, wait however long it says (can't remember), then dump and flush. As a regular chemical, the way you use it will go against most stuff you have ever learned, but rest assured that works to. It has to have "stuff" to work, since it feeds off of it.