black water tank registering 1/3 full when it's completely empty

[Interpreter Services NE]

Just wondering if anyone has had this problem before...we recently took our Grey Wolf 26bh out for the first time...this was also my first time trying to figure out the holding tanks...we had no issues filling them whatsoever but when we went to dump the tanks I followed the directions step by step and thought I had fully drained the tanks (there was no more liquid coming out)...when I went to check on the sensor it indicated that the black water tank was still 1/3 full...which makes absolutely no sense...we flushed about 2 gallons of water (through the toilet) to see if there was a clog or something...but nothing...we repeated this process 2 more times and nothing...has anyone ever had this problem before???

[chevy02]

It is probably just something caught on the sensor this will happen a lot just fill and flush several time to clean tank real good. There is a lot of discussion about this on here some people use calgon softener in there tanks some people put ice in tank and ride around you will just have to see what works for you i do put calgon in the tank before we leave on a trip let it splash around and coat the tank seems to help THe best advice is to fill it full with water before dumping and do this a time or two if you can then you know its empty no matter what the light says you probably have a 25 or 30 gal black tank takes a lot of use to completely fill this tank.

[Herk7769]

You will find all you need.

There are even photos that show why the "empty" light is always on and why the 1/3 light is a "not empty" light.

Deck angle will turn on the 1/3 light as water held by crud on the walls drains to the bottom of the tank and turns on the "not empty" light.

Black Tank 1 pictures from travel photos on webshots
The "Empty" light is actually a "Power On" light.
The bottom stud is the "not empty" light.
The middle one is the "Half Full" light
and the top one is the "Dump me soon" light

NEVER dump until the Dump Me Soon light is on.
If you MUST dump before then, flush toilet until the "Dump Me" light is on and then dump. This will make sure all solids have enough water movement to move them. After dumping, flush if you have a turbo flush or a flush cap. Then add the chemicals (2 Capfuls Calgon and your odor control chemical) and follow with a MINIMUM of 2 gallons of water.

[aintgotnun]

Ah the infamous black tank lights. A little bit of TP or other "solids" often give false readings. As stated above, try to dump when at least 3/4 full. You can shine a flash light down the toilet to have a looksee at actual level when getting fullish. When it comes to chemicals and such.. I stopped using any chemicals after I installed an RV360 on the black tank vent. Since the addition of the RV360 I've never had an issue with the wonderful smell associated with black tanks in my rig. It's paid for itself over many times in chemical costs. YMMV

[Interpreter Services NE]

thanks so much for the quick replies...I will try the different ideas of using calgon, ice, or a series of flushes to get this light back down to empty....I have also considered the addition of other addons like the RV360 or some Camco tank rinser products...I will post my solution to this problem once I try the different options given...thanks so much...

[masonga]

Originally Posted by aintgotnun

When it comes to chemicals and such.. I stopped using any chemicals after I installed an RV360 on the black tank vent.

What is an RV 360 and how does it work?

[Herk7769]

If you look at that photo of the sensors it would have to be a HUGE piece of TP to span from the ground stud (on the lower left of the outlet) to any of the lights (studs on the right of the outlet).


0910091059 pictures from travel photos on webshots