Was wondering the same about the Brix foliar. I usually mix 8ml with 8-10oz water and still have a lot left over. But have to use that much to make sure the sprayer will pick up the liquid. If I had a more effects sprayer, I’d probably use what Ween uses or less since I only grow 1-2 at a time.
Brix is mixed at 1oz per quart of water. So, that's roughly 1 ml per ounce of water.