Have you tried diet sodas, diet coke, stuff like that? You can try any fizzy drink ( coke, pepsi,.....) as well. They are extremly acidic (pH of Coke is 2) and diet fizzy drinks are containing aspartam which sways pink by itself.
I used to drink at least 3 large glasses of Coke every day and my pH was 4. I have 2 girls.