Black Tank - Check my Math..

[LarsMac]

I think you got it figured out. They are notorious for inaccurate readings.

Yep. Our tank can be perfectly clean and showing nothing in it. We get down the road, flush a time or two, and suddenly, it's showing 3/4 full. Then never changes for the entire trip, except when it is actually completely full. then still shows 3/4 after a cleanout.
I saw mention of some aftermarket sensors that were supposed to be far more accurate. Thinking about getting those, but then we are pretty good at telling when it's time to empty, now, do not high on the "gotta have" list.

 

[Rene T]

Yep. Our tank can be perfectly clean and showing nothing in it. We get down the road, flush a time or two, and suddenly, it's showing 3/4 full. Then never changes for the entire trip, except when it is actually completely full. then still shows 3/4 after a cleanout.
I saw mention of some aftermarket sensors that were supposed to be far more accurate. Thinking about getting those, but then we are pretty good at telling when it's time to empty, now, do not high on the "gotta have" list.

Valterra makes a replacement sensor for black and gray tanks. A set of four cost $28.00 on Amazon. For the black tank, the sensor has a canopy over it and the goal is to keep crap off from the sensor. Just Google “rv black tank sensors” and they will come up

 

[Martian]

The right tp goes into solution within a short period if there is sufficient liquid in the tank. Get three glasses and fill with water. In one, put a sheet of single ply such as Scott. Put a sheet of double ply in the second and a sheet of triple ply in the third. Come back in an hour and check and then in two hours and also in three hours.

 

[Trivet]

No we don't but unrolled it's larger.

I'm no mathematician though.

Maybe larger looking, but it's the displacement of water the toilet paper creates that is at issue. With an unrolled roll, all the areas of air within the perimeter will get filled with water.

We get longer by not putting as much TP in our tank.

How are you determining when your tank is full? You said "maybe it's our sensor" when you said you went from getting 5 days on a tank to 14 days on a tank. As people have said, sensors are notoriously unreliable, so it could have just been wonky sensor readings that happened to correlate with your putting toilet paper in a bin instead of in the toilet. And really, there's just no way reducing toilet paper use by one roll in a 40-gallon tank could lead to getting three times more capacity in that tank.

 

[Vanha Pieru]

i know, this is an older post. But seems relevant anyway.
We have Dometic 8700 macerator toilets in our 2015 MH. Recently the local store was out of the regular Scott RV tp, so I bought some Camco rv tp.
Do NOT, repeat: DO NOT, use this stuff if you have this toilet. Within a day after starting to use this stuff both toilets were plugged. I thought we had used Camco before with no problem, but these rolls are like 200 grit sandpaper( Not that difficult to remove the toilets and clean out the clog, but not my first choice for a Saturday morning activity!
Good luck