Do Calcium levels and Alk levels always deplete in lockstep?

[jg013c]

Well I have restarted a low-concentration drip of Kalkwasser. I used 1 tsp per gallon of top-off (I am gonna move to 1/2 tsp. for the next gallon). I tested before the week of dripping and after the week of dripping. My pH went from 7.9 to 8.2 and my alk went from 4.0 to 4.4 (a little high, but probably no big deal) and my calcium stayed at 440.

If kalkwasser raises alk & calcium at the proportion used by the aquarium then how could it be that my alkalinity raised while my calcium did not?

Can this be attributed to imprecise testing? Can this be attributed to the alkalinity of kalkwasser testing differently than the alkalinity of baked baking soda? Is there something that can reduce calcium relative to alkalinity?

This is not so much a clinical problem, as I will simply reduce the concentration of the kalkwasser & then add a small amount of calcium chloride if needed to regain balance.

My question is theoretical.


Thanks!

[Randy Holmes-Farley]

Alkalinity always moves up and down a lot faster than calcium (20 ppm calcium for every 1 meq/L (2.8 dKH) of alkalinity, either added or removed in any balanced method). Couple that with lack of perfectly accurate test kits, and the result is not surprising.

This article has more details:

When Do Calcium and Alkalinity Demand Not Exactly Balance?
http://reefkeeping.com/issues/2004-12/rhf/index.htm