In the root treatment, I was taught to tonify Ki (Qi), but I was not taught which Ki to tonify. At that time, I was using sharp silver needles, but the depth of the needle varied even if just touching or pressing the skin so I think tonified Ki was changing depending on the depth of the needle without knowing it, or it might become dispersion when the needle was pressed on the skin. Yang Ki can be equal to Defensive Qi and Yin Ki can be equal to Nutritive Qi.
Is it necessary to use Yin Ki and Yang Ki separately?
Even if the same point on the same meridian is used, the result is different by which Ki to use. One makes the pulse, abdomen tighter and/or faster. Another makes the pulse and abdomen softer and/or slower.
So how can we decide which Ki should be used for the root treatment?
One method is to check by light stroke on the meridian. For Yang Ki, stroke fast and lightly. For Yin Ki, stroke slowly and a little heavily. If the pulse, abdomen and muscle tension get better after fast and light stroke, Yang Ki is good to use. If slow and a little heavy stroke makes the pulse and others better, Yin Ki should be used.
Another method is to check the pulse quality. If the pulse is pounding, Yin Ki is applicable. This is introduced by Mr. Niki who is an acupuncturist in Japan and I always use the information on his blog as references. To confirm whether or not Yin Ki can be used, light stroke on the meridian should be done.
Now this is my method or my hypothesis.
Above the abdomen, turn your hand clockwise around the navel while you are checking the patient’s pulse. If the pulse gets better, that means slower and softer, Yang Ki is good to use for the root treatment. When the pulse gets better when you turn your hand counter-clockwise around the navel, Yin Ki is good to use.
First decide which side of the body you will use (Refer to http://www.cozyacu.com/blog/relationship-between-treatment-side-and-micro-cosmic-orbit). Once you decided the side to treat, decide which Ki you will use by the above method. If counter-clock seems good, perform slow and a little heavy stroke on the meridian which came up by your diagnosis. If the pulse, abdomen and muscle tension get better, you can tonify one of the points on the meridian. If not, you should choose another meridian.