I added a sprayer to my Gray tank last year because my sensors were wonky...now they function like new again. I don't flush every dump, maybe a couple of times a year and the tank walls stay clean enough for the sensors.
One thing I discovered was when the grey tank filled to the level of the sprayer I occasionally had a water drip, the back flow valve needed to be pressed and popped back into position. To avoid future leaks I use a screw in plastic plug designed to plug a hose, the kind you get from camping world for a couple of bucks. They are more secure than the rubber press in ones.