[JRTJH]

Like Tony and others have said, You'll know when the black tank is full, no reason to fret over it.....

In every trailer I've had with tank gauges, the black tank sensors have fouled and have read incorrectly. Usually it always reads 3/4 or full. Also, in every trailer I've had, the toilet has a "peculiar sound" when the tank gets close to being full. We have learned to rely on "toilet flushing sounds" to tell us when the tank is nearing full capacity. We've found that the sounds are far more accurate than the gauges ever were.

I'd think that if you pay attention to what your toilet is telling you, you really don't need the gauge anyway. For us, from 1967 until about 1993, none of our trailers even had a tank gauge. We did just fine "back then" and the only thing that's changed is a set of buttons and LED's on the wall that usually don't work anyway. This is one time when KISS really works as well (or even better) than "modern technology".....