I would not trust that site. The only justification they give is that birds prefer acidic water. This is an unfounded statement showing no reason to believe their claim.
As I said, I do not know of any valid reason to acidify water for poultry.
My birds have shown a preference for my high...
Your Broad Breasted White turkey may be suffering from coccidiosis.
If it is Blackhead, she would have yellow droppings.
Post pictures of her droppings for @casportpony.
If it is coccidiosis you need to get her on Corid immediately.
BTW, there is no such variety as a White Breasted turkey...