Okay good point. Lets see what people key on more, calcium or alkalinity keeping in mind it would be regarding mostly LPS. I've heard them same from a shop I buy alot of my corals from so we have two for alk. anyone else?

Watch your Alk as it drops much quicker.

Alk and Ca consumption are equal in a reef tank. LPS, SPS it doesn't matter. Your Alk will fall considerably quicker that Ca. Alk in comparison to ppm at 7.0 dKh is equal to approximately 200 ppm or 1/2 the volume of Ca (400 ppm).

For every 20 ppm of calcium used, 2.8 dKH of alkalinity will be used up.

For an LPS system I find it can often be maintained by just using waterchanges with slightly higher values than you're aiming for. For example add a bit of cal/alk/mg as needed to achieve cal 440, 11 dKH, 1450 mg in the freshly mixed saltwater. Use this slightly saturated saltwater for 10-20% weekly changes and you may not need to dose the tank directly.