How much Hydrogen peroxide; how many ml or teaspoons do I use?
If you are using a 3% hydrogen peroxide. I estimate a reasonable figure is 1 tablespoon per 1 glass of water for washing or soaking your hair. Add about 6 tablespoons of apple cider vinegar. Of course, if you want a stronger solution, then 1 tablespoon of hydrogen peroxide to 1 glass of apple cider vinegar. Again, you have to try to see if my recommendation is too strong or too weak. Some people told me too strong, because their scalp has open wounds, some say too weak because they still feel itching.
If apple cider is too expensive, than use vinegar. Add borax until the borax cannot be dissolve any more (I estimate about 1 tablespoon of borax). Leave it on for several minutes.