I thought I had black tank odor about a month ago and I couldn't seem to stop it. After giving up on the black tank, I put a load of chemical in the kitchen gray tank. Odor gone! Even with regular dumping the gray tank needs something added to it occasionally. I full time and this is the first time in over 3 years with this problem.
2006 GMC 2500HD CCSB 4x4 Duramax/Allison, Titan 52 gallon fuel tank, Prodigy Controller, B&W Companion Hitch
2010 Jayco Designer 35RLTS, Cummins/Onan RV QG 5500 EVAP, Progressive Industries EMS-PT50C, TST Systems 507 TPMS, RV Flex Armor Roof