Liquid is your friend in the black tank to keep 'Mt Everest' from forming... The Tornado rinser will definitely help as well.
The black tank valve should normally be kept closed - even when hooked up to sewer connection... When it fills - dump it, add new chemicals with fresh water and start over. We find with 2 of us - we typically dump black once a week... I close the gray the day before to collect some water... Dump black - run tornado rinser for a few minutes, close black, and open gray...
Not yet retired...
Florida (Michigan transplant)
2014 Hurricane 32A
2000 Infinity (previous)