I’ve had the CMC bottled for a month now. I can see tiny mold spots growing on it now, but I can still use it. I initially mixed in 0.25% Sodium Benzoate as a preservative. I say as a preservative because that is what every food stuff that uses Sodium Benzoate says. I have very little clue about what it might be doing but I will keep this post updated as the time passes to see how long it lasts. I’ve used only maybe a 5th of the total 600ml or so that I made at 2% ratio to water. In this sodium benzoate ratio I haven’t seen it form the precipitate when mixed with an acid yet, so there is a quantity as which that happens. Also I think its reversible because I can dissolve the precipitate with a good microwaving and mixing.