When Tom Barr did a talk for us in September, he stated he targeted about a 5.0 dGH and didn't worry too much about dKH as long as it is above 2.0.
I use Seachem Equilibrium to raise my DGH because they have a dosing calculator
. I used to use equal parts of CaCl (Dri-Z-Air) and MgSO4 (Epsom Salt) but Equilibrium is easier.
To raise dKH I use NaHCO3 (Baking Soda); here is the calculator
I use for dosing.