I think you may be refering to a Black water flush system. we have one on our 04 Safari and for us it's not worth the price of a Big Mac. It hasn't worked right after just a few times. Talked to the mfc of the system and they told me to use Ka Boom and try to clean the spray head and if that didn't work, the spray head would have to be removed to clean. We use a Flush King and really feel it does a good job of cleaning the tank. The Flush King is available at most RV stores.
Home of the Wayward Wind
Bogfrog & Mr. Turbo
If in life you stumble, make it part of the dance