Hello, we are new RV’rs and I think we may have not had enough water in our black tank when we first used it, and I fear that we have some dry waste in the tank. How would be the best way to flush it out when draining? We have a Launch Starcraft 24RLS with 31g tank.Lot of water. If on full hook up leave the valve closed till tank is full. Drain black tank before Gray. Does your RV have a rinse built in? If so rinse good after dumping. Get some kind of rv holding tank chemical for the tank to put in it. Be sure to use approved toilet paper. Welcome to the forum Nick. Let us know how the trip turns out.