Completely fill grey and black tanks, Hot water if possible, overdose it with Dawn dish liquid. let set overnight. Buy a Valterra A01-0187VP Flexible Tank Wand by Valterra $ 16 95 Amazon. Drain tank. On the open black tank drop the wand turned on high slowly down the commode slowly spinning it. take it down as far as you can even till you do not see it and you are spinning it by the hose. Do not be in a hurry, let it blast the tank. Now drain the grey tank and do the same thing but go into the dump opening. The statement above " to use septic safe toilet paper as it breaks down easier in the tanks and is less likely to wrap around or attach to the sensors." I don't agree with. If you take any brand of toilet paper and put a sheet in a glass of water and let sit overnight it will be like mush when you try to pick it out.
