[Randy Holmes-Farley]

oh and why not use a strong Kalk Solution for this....that's pH 12.0?

In terms of neutralizing acid, baking soda is as good or better than limewater. While the pH of limewater may be 12, you can add solid baking soda without adding a lot of water volume, and a gallon of limewater is only as good for neutralization as maybe 4 teaspoons of baking soda. You also will not overshoot the pH with baking soda.