Black tank and toilet paper and chemicals

We use the Costco tp and have not had any problems. The main trick is to make sure your black tank is almost full before you dump it even if it means holding the toilet valve down for five minutes letting it get full. We also have a tank cleaner installed (don't know what brand as it came standard with the Open Range but had a Tornado on our last trailer) and use it every time we dump the black tank. We do use chemicals too (a liquid) but I don't remember what brand. If your tank has solids built up now, you may need to use the Geo method (do a search) to get it cleaned initially and then try what I have suggested. Happy camping.