Maybe I said this to you before... Have you tried using hot distilled water to dissolve the BS to do the BS/ACV wash and rinse? (Or any wash/rinse for that matter?)... Also, you may want to try the Mosalu soaps from Etsy - I had an issue with dandruff, and alternating between BS/ACV and the Mosalu seems to have solved it. the folks here also recommend a cold water rinse before you step out of the shower. Then between showers, i massage my scalp to stimulate release of dead skin and improve circulation.
My water is funky - it's hard water, with a softener; but something is wrong with my softener, so I get buildup and dandruff if I deviate at all from my wash routine. It's to the point where if I experiment with anything, I make sure I have no where to go that day
Another tip that works for some people if to boil the hard water first, then let it stand to let the heavy stuff settle to the bottom of the pan. Then pour off and use everything but the last bit in the pan; leaving much of the mineral problem behind. Cheaper than bottled water...
PS - dreadlockshampoo, with my strange water, makes my head smell like something died. I love her products, but something just doesn't work for me there. That's another reason I tried the Mosalu.