Paint

[JRTJH]

^^^^ X2 (what Chip said)...

It may sound "overly simplistic" but the black tank is nothing more than a "bucket of poo" (with a lid on it). You can add all kinds of "monitor systems" or "detector systems" but when it's full, it's full (no matter what that push button light thing says)....

On every trailer we've ever owned (50+ years worth means many more than a few) we can tell when the black tank is approaching full. There's a distinctive change in the sound when flushing for about the last 10 or 15 flushes. That's usually a "full day of business" before nothing else goes down the chute....

Through experience, we "know" that we can dry camp (or camp with full hookups) for 4 days before we start 'getting close" and we can estimate when the flush will start "sounding different. I honestly can't remember the last time I pushed the button to see how full my black tank was. For me, it's more a "check the registration date on the pole in front of the campsite for the number of days so far".... I've found that to be just as accurate (or maybe even more accurate) than the monitor system with all those fancy lights that blink (or don't)...... KISS, it worked with chamber pots, it works with black tanks too ......