Black Water Tank Sensor

[terry.etapa]

My 2024 R31 black water tank was pumped out at Elliott Bay Marina, but the tank gage still shows full. Is the sensor an internal float or is it external?

 

[Rauguthj]

Sometimes ours takes some time to change to green. Flushing the tank with water a couple of time when pumping out helps as well.

 

[Full_O_Fish]

Most of the tank sensors on rangers and cutwaters are just adhered to the outside of the tank with either two or three sensors (empty and full or empty, middle, full). If the tank has not been flushed out with additional water following discharge once or twice, occasionally debris can be stuck to the inside of the tank at the location of the sensors causing the readings to not reset or be accurate.

 

[terry.etapa]

Thanks. I now know it’s not a stuck float.

 

[Mike and Sarah]

It helps to fill the tank up at least to 1/2 full with freshwater a couple times after pumping out. Pump out each time. So far after 3.5 years we have had no trouble but you never know when it might happen.
Also if you pull out the floor in foot of the bed you can see the tank and sensor. We use a flashlight shined on the tank to see if the tank is building a scum line

 

[MOwcean]

I have had the same issue and assumed I would need to replace the sensors. If it is cause by a scum line, how do I remove that? I don't think filling the tank with fresh water will do that??

 

[Rocky Lou]

Mine has never shown anything but green, even when it's clearly 'not'.

 

[Mike and Sarah]

I have had the same issue and assumed I would need to replace the sensors. If it is cause by a scum line, how do I remove that? I don't think filling the tank with fresh water will do that??

From what we have heard is you can add washing machine soap and water softener to the tank. Then fill up the tank over 1/2 with water. Go cruise around for a while and allow. It the mix in the tank. Then pump out and rinse a couple times too.
Others mentioned dishwasher soap too.
Still others mention adding bunch of ice and water to the tank. Do not do this through the toilet. You will destroy the macerator for the toilet. There is not a good way to use the ice method on our boats.

We have also gone to putting used toilet paper into a small trash can that uses doggie poo bags.

 

[fishheadbarandgrill]

Our sensors are laying on the deck next to the tank and they always read green. We use Borax and water softener occasionally to clean.