My pool builder's concrete sub actually used liquid dish detergent on the coping to keep the concrete from sticking to the part that's supposed to show when they were pouring my deck this past April. There were a few bubbles that formed in the water when they went to wash it off, but they didn't stay in the water long...water looked "normal" again within an hour or so. I don't know if that helps or not, but that's my experience with liquid dish detergent and pool water.