I don’t know if I am just the only person that have had a problem these problems, but all the suppliers I called did not know what to do. OK, I grouted the floor and when it dried it was spotty light and dark. I ended up calling the manufacture and they said it was efflorescence. This do to with the dry of the grout which I should have thought of, because I have had this happen on colored concrete and grout is basically colored concrete. Anyway, the manufacture said to wash the grout with Sulfamic Acid Cleaner let it dry, clean it and reseal it. Perform all of this work per the instructions on the bottle.
This worked, but you need to clean the floor really good after you do this, because when I sealed the grout I had problem with the sealer that got on the tile. Just a FYI if you have sealer problems just reseal your floor and buff it dry with a towel.
Also don’t forget this is a acid product you a working with so please be careful what you get it on and don’t use it on product not recommended by the manufacture. If you are not sure and the manufacture and ask if the product will work on your tile.