Let me throw some number at you...and I will round off to make it easier.
When calcification occurs, a set amount of alkalinity and calcium is used. For every 2.5 dKH
used, 18 ppm
of calcium is used.
Let's assume before you did any dosing, your alk
and calcium were in the normal ranges of 9 dKH
and 400 ppm
According to the directions from Kent, 1 teaspoon per 40 gal
of water will raise alk
You are currently 10 dKH
above "normal', which means you would have had to put in aprox 7 teaspoons in your 16 gal
tank just to get it that high, but.......
Your calcium is aprox 270 ppm
below normal. For it to drop that much, calcification would have had to "use" 34 dKH
Now you would have had to been at 54 dKH
at the high point, which means you would have had to have added 36 teaspoons of supplement.
(It's early so the math may be off a little, but you get the idea)