I agree about the rather dramatic action to drop something like SO4/Cl ratio from our vocabulary. If there is evidence that we should, I'd really like to hear from the advocates of such action the basis for that. So far, I haven't heard anything substantive. However, I do agree that focusing on the ratio at the expense of PPM is not what I've read anywhere in the realm of those who should know. I just know that when I started to use it, I got some pretty convincing results.