Grey Water Tank is draining really slow now....

I am sure that grease is the culprit. The tank drains into a 1-1/2" pipe before meeting up with the three inch drain from black tank. I attached one of these backflush adapters and blocked off the black tank, obviously, to force water back into the grey water tank. Seem to help a little.

I told the wife to be sure to wipe all plates with paper towels before washing in sink. Do they make a chem that will break down greases or oils.

Anyone have a solution?

Jeff W Waldrop