I use a quickie flush in my grey and black tanks. I am 99.999999% sure I don't have any thing hanging on the walls or the bottom of the tank. over the year I have read about the proud owners of the flush kings and how good they are. if they are so good then why are the TT manufacturers putting quickie flushes in there TT;s and not flush kings? having said all that, I do put some pink in the black and the grey tank, probably about a qt., each. that is just for the seals to keep them moist. the grey tank gets it's share by way of the faucets and the "P" traps