Sounds to me like you have a case of the "piles". Just cleaned one out for a friend tonight - crappy job! The way most of the RVs are made today result in a black tank that is 6-12 inches deep. The toilet line enters the tank on the shallow end of the tank - perhaps 3-4 inches. When we flush while trying to conserve water the solids (poop & paper) tend to accumulate at this entry point. Often when you dump the tank a small "pile" is left. When you next use the toilet the pile builds a little more until you reach a point it is backed up into the inlet pipe.
If your toilet is still backed up, use a snake (or a straightened coat hanger) to clear a small passage. Then put a hose with a rag wrapped around the end to form a tight seal in the bottom of the toilet bowl. Recommend a shut off valve on the hose VERY CLOSE. Apply a little pressure to the "plug" and hopefully it will free up and flow freely. Once you get it flowing use a wand to thoroughly clean the inlet to the tank. Here is a good wand to use: http://www.amazon.co...black tank wand
In the future, ALWAYS use plenty of water. We usually will fill the bowl about 1/3 full before "doing our thing", flush when finished, fill the bowl 1/3 again and flush again. This helps to "push" the solids into the tank better. Might have to dump the black tank more often but it sure beats cleaning out the "pile".
Try not to dump the black tank until it is nearly full. This allows the solids to dissolve and flow easily out of the tank. If you do dump before it is at least half full, use your black tank flush to put extra water into the tank before dumping. My tank gauge is a joke and never works. I wait until the toilet burps (tells me the vent pipe is blocked) before I dump whenever possible.
As for the toilet paper to use - RV toilet paper IS NOT needed. Any septic approved paper will work fine. To test it take 2-3 sheet and place it in a glass of water, shake it briefly and if it disintegrates it is fine to use. We use White Cloud 2 ply and have not had a problem as long as we use plenty of water as noted above. In fact I strongly urge you to put about five gallons into the tank after you dump each time.
As for chemicals, we never use them unless there is a significant odor problem - typically very hot weather.
The plumber snake I carry came in handy tonight. Managed to unplug the toilet with only a little splashing inside the bowel itself! Rubber gloves were nice though!
Another accessory I will not be without is the Flush King: http://www.campingwo...=p_sort_default
Hope this helps.
USN Retired (1983)
Electrical Engineer, Tektronix, Inc. 83-99
2002 Winnebago Ultimate Freedom
Full time from 1999-2011 in a fifth wheel
Now part time