RV Staff Report
When you have full hookups, leave both the black and gray water valves closed. This allows solids and tissues to start breaking down and liquefying so they will flow better.
When your black tank is about half full, empty it followed by a good flush from your gray tank. The gray water will thoroughly clean out your dump hose.
When you leave the valves open you are likely to have bad odors, create a build-up just below your toilet discharge valve, accumulated waste will collect in your dump hose causing even more odors, and un-flushed matter will collect on the bottom of your holding tank and harden becoming almost impossible to clean out.
Use a board or commercial product (like the Slinky shown in the photo) to lay your hose on that will maintain a slant between your hose outlet and the dump station to create a better gravity flow and no low spots where waste will collect.