We use a capful of Calgon liquid in each tank, and sometimes add like amount of laundry detergent to black tank. Add about 4 gallons of water to each tank AFTER dumping. Run to next campground.
No, the monitors still don't work, but we feel it helps clean the gunk nonetheless. Don't care if the monitors work, don't like the thought of excess gunk, ewwwwwwwwwwwww.
Don't use hot water, don't use ice (how can you get it in the sink other than using it crushed?? why waste good crushed ice, save it for the margueritas
).