MgCl2 and MgSO4 in a 5 to 3 ratio.

[rkb]

Recently I picked up a 3 part kit from my LFS and upon further research developed some questions. In the kit for the magnesium they used only magnesium sulfate and no magnesium chloride. Many recipes including the one at BRS utilize MgCl2 and MgSO4 in a 5 to 3 ratio. The claim made by my LFS is that the MgSO4 will maintain/raise the magnesium levels in reef aquaria. It seems to me that in the most current magnesium recipes MgSO4 represents roughly 37.5% of the mixture underscoring the importance of MgCl2.

So with that in mind what is the importance of the ratio. Does it create some form of balance or make the solution more stable?

Thanks
R

[Randy Holmes-Farley]

BRS uses my newest recipe,

An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System
http://reefkeeping.com/issues/2006-02/rhf/index.php

and the LFS may use an older one that has too much sulfate in it, but is still likely OK if you cannot obtain magnesium chloride.

A Homemade Two-Part Calcium and Alkalinity Additive System
http://www.advancedaquarist.com/issues/april2004/chem.htm

I discuss the two different recipes here:

http://reefkeeping.com/issues/2006-02/rhf/index.php#21