I am trying to make sodium hypochlorite by electrolysis using a 12v 1.5 A power adapter with salt solution and carbon electrodes, in a sealed container but for a tiny hole to allow release gas pressure from any gases evolved. As I understand the solution is supposed to turn greenish yellow, but I don't see any yellow. I continued electrolysis for 5 more hours, still no colour change, only black carbon like particles settling at the bottom, but it does smell like chlorine water. So I left electrolysis to continue overnight, and still no yellow. Instead the whole solution is black-ish. The black is maybe from the rubber used as a plug in the container that is corroded by the chlorine. What am I doing wrong ?