Shampoo build up removal

I have thick, wavy colored hair on the dry side, and I like Terax Latte shampoo. It is a clarifying shampoo that doesn't strip your hair in the least, which is not easy to find.
 
I add a teaspoonful of baking soda to my regular shampoo.
The baking soda changes the PH of the shampoo.

Works like a wonder! ;)

I also use a rich conditioner on the ends of my hair after using the above remedy.
 
How do you know if your hair has shampoo buildup?

You get filmy gunk on your scalp. You can see it if you scratch your head ... it gets under your nails. It isn't flaky like dandruff.

Thanks for the baking soda recommendation ... I am going to give that a shot this evening.
I'll also try the apple cider vinegar remedy. If those work well, I can save some money and not have to buy an expensive remedy shampoo.
Thanks for all the suggestions!