Gray tank not draining fully

GregReese · July 15

Hi folks,

We have a 2022 Tab 400. The gray water tank seems to be filling up quickly. We just drained it and with no water coming out we still had two lights lit on the gray-water meter, I.e. 1/3 full. A few days ago we put 1 cup of Dawn liquid soap down the sink and ran some water, drove around and let it sit a few days. That didn’t seem to help. We checked the gray tank air vent and nothing was blocking it. We ran some water down the vent and it came out of the drain hose fine. I was thinking I could drain as much water as would come out, then pour in a measured amount of water to see how much would go in before the sensor said the tank was full but that wouldn’t tell me if the tank was clogged or the sensor was faulty.

Any ideas?

Thanks.

Greg Reese

P.S. - The black water tank is working fine.

subkron · July 15

I have a water flow meter that I find useful.
https://www.amazon.com/dp/B0DNPLYVSJ?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_5

I've used this to fill my grey tank so that I could add a cleaning solution and then letting it sit to "try" to clean the sensors. Problem is, even with this method my grey sensors don't go down to 1.

Note" the tank is spec'd for 18 gallons but I had it get full (water out of shower drain) at less than that, somewhere between 15-16 gallons, trailer level.

I find my my tank sensors are wonky at best, they always seem to be off. I can get the black tank sensors cleaned off with one of those wands down the toilet but I wish there was a similar method for the grey tank.

MuttonChops · July 15

@GregReese
The LED style tank monitor nüCamp now installs is a known highly inaccurate tank monitor method and that has been the case for decades. But the monitor is cheap and has RV Manufacturer Custom Brand Marking options so nearly every RV has that near useless monitor.

Before ~2020 nüCamp installed the SeeLevel monitor which is not prefect but 100's of times more accurate . . . and was more expensive for nüCamp to purchase/install (labor) and service under warranty when sensors did fail. So as production volume increased nüCamp opted for what is best for them not the customer IMHO.

First modification in any future trailer/camper I purchase will be adding SeeLevel.

Trailpixie · July 15

Is there a practical way to install a new monitor? Do you need to get inside the tank to install a sensor?

Binghi · July 15

The gray water tank in our 2021 400 doesn’t seem to hold the amount of water that it used to, so it fills up quickly like yours. Real irritating, especially when boondocking. I suspect that sludge buildup over the years has reduced the capacity of the tank. The tank sensor lights on the wall panel never have been accurate, so I don’t rely on them. We know the tank is full when the kitchen sink stops draining.

I bought a 3-foot flexible tank wand and plan on using it to dislodge as much crud as possible by spraying water into the tank using the shower drainpipe and the gray water discharge drainpipe. After that, I plan on pouring Dawn soap into the kitchen sink drain on a regular basis. Hopefully the tank will regain some capacity.

MuttonChops · July 16

https://tab-rv.vanillacommunity.com/discussion/comment/222356#Comment_222356

When I was considering switching to a TAB 400 I did a little preliminary research.

SeeLevel Sensors glue/tape to outside of tank so underside airflow cover must be removed.
SeeLevel can use the installed wire from tank to monitor panel.
SeeLevel has a different display panel that has to be mounted.
1. I was planning to cut a hold in the nüCamp panel in area of the LED monitor.

So doable but not a basic modification.

Gray tank not draining fully

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