Starter really likes whole wheat, whole grain, spelt, or rye flour, but I've always just used what I have on hand, which is usually bleached all-purpose flour, and it works just fine.
Starter really likes whole wheat, whole grain, spelt, or rye flour, but I've always just used what I have on hand, which is usually bleached all-purpose flour, and it works just fine. Don't obsess over the flour unless you really want to! Just use what you have.