Black Tank flush with valve closed

After I dump I flush the tank with the cleaning wand installed in the tank. If you don't have one in your tank you can purchase one at most camping stores or on-line. I do this with the valve open and then with the valve closed for about 5 minutes. Occasionally, I have gotten stuff caught in the pipe. If that happens I do a reverse flush from the valve using a hose and an adapter that allows water in and sewage out. I am a full timer, so the rig sits for months in one spot and does not slosh around as one will do when traveling. When done, I fill the toilet with water and chemical then flush. Done!