My trailer is much older and no doubt has a different system - but it has never worked properly, same with the trailer I had before!
I did think that the newer ones are supposed to be much better.
I haven't heard much success with the ice cube idea but couldn't hurt to try I suppose!
In our case I have just learned over the years net to even bother with the tank monitors - they are not a whole lot of use for anything.
In our case we are almost always on full hookups anyway so it is not a problem.
The odd time we are not on full hookups, it has never been more than a week and we have never really run into any issues.
You can tell the black tank level just by looking in the toilet! In any case, I know we can go a month without filling the black tank.
We don't use much fresh water because we carry drinking water separately, and use CG showers when we don't have hookups, so I have never really been concerned about fresh water level - we have never run out.
As for gray water, I have quite a few tricks to avoid filling it when we are not on full hookups, I think it has happened once or maybe twice in eight years - when gray water backs up into the shower pan, the gray tank s full and time to do something!
So I just don't bother at all with my useless tank monitors!
Brian & Connie Mitchell
2005 Classic 30'
Hensley Arrow / Centramatics
2008 GMC Sierra SLT 2500HD,4x4,Crew Cab, Diesel, Leer cap.