[rdunk]

Glenn, our black tank is 50 gal. Yes, the tank sensors often become dirty and not read correctly. Do you use any type of chemical in your tank? Some of the chemicals can help with both the smell and breaking down the "stuff" that can "cloud" the sensors. When the tank gets pretty full, the smell does creep out when flushing the toilet, especially when the vent fan is running. That is also a pretty good indicator of the need to flush the tank. I do find that the near filling of the black tank a couple of times when flushing helps clean the sensors.

How often you need to flush has a lot to do with how much water is kept in the toilet. While these toilets can be flushed with very small amounts of water, many of our DWs (dear wives) like to fill them like a stick house toilet (with a lot of water). Thus, the likely need to flush every 3 or 4 days!