Bobbo wrote:
A mound in the tank causes problems, but not THAT problem. It doesn't block the air from escaping the tank on flushing.
I'll have to disagree with that - I've experienced it personally on 2 different RVs. Our current RV has a black tank that is fairly shallow right under the toilet opening, and then deepens out; like a "step" feature. When we're sitting for a length of time when we flush everything hits the shallow part of the tank and can build up there with no movement to push it to the deeper part of the tank. When we're moving every day the pile gets moved by the movement of the RV on the road. We know when there's a big pile because the toilet burps when we flush. Using a hose to force that pile into the deeper part of the tank works every time.