Watch your alkalinity closely!

[KrazyPlace]

http://reefkeeping.com/issues/2004-12/rhf/index.htm

This is a really good article if you haven't read it yet. I wonder how many of us are focused on calcium concentration instead of alkalinity?

I've never "crunched" the numbers, but this article does. For every 10 ppm of calcium added to a tank by additives (2-part, CO2 reactor, or lime water), the carbonate is increased by 1 meq/L. What this means is that if your water is 500 ppm calcium and 4 meq/L alkalinity, then when your alkalinity drops to 2 meq/L due to the corals consumption, your calcium should still be 480 ppm.

Most of us wouldn't even think twice about adjusting the additives IF we were only testing the calcium. It is much more important to track the alkalinity on a frequent basis than the calcium.