[Stripit]

I also use the Flush King to back flush the gray tank. I also open the curb side access door and found the drain pipe screw off cap. I unscrew that cap, it connects the bathroom sink line to the gray tank. I made a small diameter hose that I attach to the garden hose with a shut-off valve and feed that small hose into that access port. This way I can back flush with the Flush King, and top flush to get rid of the exact deposits your describing. It is amazing the stuff that clings to the inside walls of that tank. I do this about once a month while we are sitting, less if we are in the move mode.