fleetwood grey water drain problems

I got the camera and checked the vent all ok. Drilled a hole in the tank and checked in the tank. Some sediment in the bottom. Flushed tank with a garden hose. Took slide valve apart and checked drain pipe Wondering if there was more sediment took a pail and slowly filled the tank through the kitchen sink, amount was right at 45 gallons. Drained tank back into a pail. Parts of a pot scrubber with sediment came out,from Where?. Installed a black water flush system to grey water tank to seal the hole I drilled in the tank. When it drains now it comes out with force and no problems with back up in shower drain.