I just got an API nitrate kit and the color chart is different from the one that comes with the master test kit. The one in the individual kit makes more sense, it's a lot easier to use. The one in the master kit shows 10 and 20 as virtually the same shade...I always had the hardest time differentiating between the two. The one in the individual kit shows 20 as being the red shade that the master kit says is 40. Do you think this new one I got is an updated version? Has anyone else noticed this? I just want to use the correct one.