Bs/avc wash.
Dread Maintenance
I have hard water and it does not affect the baking soda (BS) wash. Mix 1/2 cup BS to 5 cups water, wet hair and pour onto scalp...leave it on for 10 minutes. (20 minutes if needed for deep cleanse). ...rinse well....You have very oily hair it sounds like, so you may not need the apple cider vinegar (ACV) rinse. The natural oils you are quickly producing are balancing your hairs PH. If you find you hair getting a little dry feeling, then try the ACV once a week. How you use this is 1 capful of ACV to 5 cups water. Pour over head after rinsing out the BS well, rinse off right away for your scalp type. (Others with non oily hair would leave it on for up to a minute. )
With this method you don't have to scrub the scalp as it naturally exfoliates the skin, but you can scrub if you want to.
Peace