Stuff happens...but almost always, people new to the RV world do not use enough water. Look how much water is used when you flush a toilet at home...by the time the tank is full, you should have 2/3 water and 1/3 "stuff"...the force of all that water trying to drain sucks out stuff and keeps if from getting hard. But the problem now is getting stuff out...usually a sewer service comes out and hooks on to your fitting and sucks out almost everything. Then when empty, add about 20 gallons of water so you have a small lake to let things pile up. When you flush always let lots of water gointo the toilet. Keep the paper useage down...no big wads of paper..use 1 ply paper so it will disolve easy. Live and learn