so were do I find this info
Sorry. I thought a google search would bring it up. I was surprised it didn't (when I just looked). Here's the link:
http://www.ces.ncsu.edu/depts/hort/floriculture/crop/crop_PTS.htm
I've never done it. But, it gives an idea of how an accurate ph runoff test should work. I never ph my runoff anymore. I measure PPMs for salt buildup and use that soil probe I mentioned earlier. But, when I measured runoff ph I would keep in mind how long the initial saturation sat in the soil. If it was less time than the "method" I would make a mental adjustment to the reading. (And, if the amount of runoff was large, I would keep in mind how the saturated liquid may have been diluted by that fresh input. Another mental adjustment.).
I'm not sure the way I did it was too accurate. I usually refer to the academic method as an example of how casual runoff PH'ing probably isn't accurate. (Most people aren't going to do the "method" very often. It's tedious and time consuming.).