Is your black tank never empty?
I now know why my black tank is NEVER empty. Getting ready for tank rinser installation I discovered that 1/3 full sensor is about one half inch above the base or ground sensor. Both will be covered with just a couple gallons of liquid. Instructions - dump and add five gallons to keep tank wet. Duh. I am sure there is a good reason why but it is way beyond my thinking to figure out why 1/3 full sensor is maybe a gallon above ground sensor.
Suzie & Chuck USNR USAF USCGA Challenger Owners Club 2015 37KT Challenger, Demco Commander tow bar, Ready Brake, Sewer Solutions, Safe-T-Plus 41-230, 5-Star tune, towing 2017 Ford Edge FWD 3.6L V-6 four down & 385 FastTrack kayak in the basement.
Summer - Creede, CO Winter - Okeechobee, FL