Well, at least you know now and can spread the word to others if they should ask. I sometimes find that not all TJ's carry the same products in our stores down here in SoCal but you can at least check first before spending the big bucks. The bottle says "100% Pure Ascorbic Acid" on the label and it did help with some of my staining on my pool steps. I am all about saving the $$$ when we can, right? Hope all is well with your staining up in NorCal!