estimating alk?

[Joel A]

I've seen a few people do this, and i'm just wondering how they might do it..

what i mean is when someone see's a tanks PH, Calcium, and possibly magnesium levels, and they give you a pretty accurate estimation of what alk should be according to those two or three parameters.

Is this possible, or are they just getting lucky with guesses?

 

[Randy Holmes-Farley]

No, there is no such relationship for aquaria overall. Too many other factors, such as home air and water CO2 levels confound the use of pH that way, and calcium and magnesium are nearly unrelated.

But if I guess most folks have alkalinity about 3 meq/L (8.4 dKH), I'll probably be close more often than not.


This has more:

A Simplified Guide to the Relationship Between Calcium, Alkalinity, Magnesium and pH
http://reefkeeping.com/issues/2006-06/rhf/index.php

and

Low pH: Causes and Cures
http://reefkeeping.com/issues/2004-09/rhf/index.htm

High pH: Causes and Cures
http://reefkeeping.com/issues/2005-03/rhf/index.htm