Calcium Dosing

[Octoshark]

I am dosing with calcium and read somewhere that Mag needs to be about 3x the amount of calcium. Why is this?

If I need to dose calcium, and it results in a ratio of cal-mag significantly lower than 3x, then does that mean I should dose mag as well?

Thanks

 

[Randy Holmes-Farley]

It just turns out that the amount of magnesium in seawater is about 3 times the amount of calcium. Don't focus on that number at all. The amount dosed is not 3x, certainly.

This has more:

Reef Aquarium Water Parameters
http://www.reefkeeping.com/issues/2004-05/rhf/index.htm

What is seawater
http://reefkeeping.com/issues/2005-11/rhf/index.php

The “How To” Guide to Reef Aquarium Chemistry for Beginners, Part 2: What Chemicals Must be Supplemented
http://reefkeeping.com/issues/2007-04/rhf/index.php