cloud explosion

Been there done that

HI,
The trick part is calcium will only stay in solution if there's enough mag to prevent precip. so MAG is critical to prevent a precip event when you have precip in your tank it can also lower your KH and that prevents the low PH.
SO the three most be in balance it a fine edge of Calcium no higer that 450 mag around 1200, and a good KH, Unless there's mag KH and CAlcium will precip.
Theres and article about KH, Mag, Calcium that helped me.
Doug

print this and read it a few times..

A Simplified Guide to the Relationship Between Calcium, Alkalinity, Magnesium and pH by Randy Holmes-Farley - Reefkeeping.com

 

Chemistry and the Aquarium

Here is another article that will help.