Based on your floor plan I think you ae confusing which level operate what. I can see two gray tanks separated by allot of floor space and only one black tank. Your indicator panel may have 2 black tanks on it but you only have one. black tank 35 gal gray tanks 70 gal according to the specs.
Jake my sidekick (yellow Lab) 10/04 - 05/20
2017 RAM 2500 CC 4X4 Cummins Diesel
2016 Flagstaff 26 FKWS
AF&AM & El Korah Shrine of Idaho