Give up on the liquid Alk additive.
If you follow the info I gave you and bake some baking soda, thus creating sodium carbonate/soda ash, you'll find it very easy to dose daily and maintain your desired alk level.
Use the spreadsheet I gave you on that usb. The
chemicals page tells you how to weigh and bake the baking soda, and the
chemistry page you'll use to calculate how much to dose.
Buy a couple kilos of arm and hammer man.
Just do it !
