The only chemical I know for sure is Sodium Carbonate. It's the main pH raising chemical used by pool stores and pool companies, as pH Up! and other brands. But it's available at your grocery store as Arm & Hammer Washing Soda in the yellow box..NOT BAKING SODA! It's not expensive, about the same as Borax. But it WILL raise your T/A level further. Other than that, it's a mystery to me.