Black Tank Flush

I have a built in flush system. But I have no idea what the in-tank end looks like. I just know it makes an obvious spray sound when I use it. And it does seem to clean the tank pretty well. I drain the tank, then turn on the flush, close the drain valve for a couple minutes with the flush running, open the drain valve and let the tank drain again, close the drain valve for a couple minutes, and repeat until water runs near clear. Usually 3-4 times. Lots of extra bits and pieces come out the first couple drains after running the flush. Just don't walk away while the flush is running and the valve is closed.