you don't need to do an acv rinse after using soap as long as you use a conditioner after washing. All conditioners (should be) formulated to have a pH of 4.5-5.5 (sometimes as low as 4.0). If you are using a conditioner after washing with soap you should have no problems

you can also use anything that is acidic. hibiscus tea, citric acid, amla rinse etc.