While I wait for my certified 4dKH I have made my own batch using kitchen measuring utensils and TB's instructions.
It turned out over 4dKH so I added distilled water and tested, distilled water and tested again until it tested out 4dKH.
How accurate is this?

I am using it in my DC and it's looking good by using regent from an API PH test kit. Three drops regent + my 4dKH.
First it turned blue and after about 4 hrs turned green.