Ca Carbonate saturation pH dependence

[tankslave]

Randy,
I was wondering if you had the link to that one article that had the plot with a box which showed the range of values of Ca and Alk to shoot for.

The other thing, I'm thinking of dosing Kalk at night to offset the pH drop from the reactor and I was wondering if I was going to run into trouble with the Ca Carbonate precipitating out. The controller will be set to keep it 8.1-8.3.

Do you have any articles describing the pH dependence of the saturation level of Ca Carbonate?

Thanks again!
-Lars

 

[Randy Holmes-Farley]

I have such graphs in several articles, but do you mean this one:

Solving Calcium and Alkalinity Problems
http://www.advancedaquarist.com/issues/nov2002/chem.htm


I don't see a reason to worry excessively about precipitation of calcium carbonate unless the alkalinity is very high (about 5 meq/L; 14 dKH) the pH is above 8.5, or mangesium is very low.

As a rule of thumb, each increase of 0.3 pH units about doubles the supersaturation of calcium carbonate.

I discuss such issues in this article:

Calcium and Alkalinity
http://www.reefkeeping.com/issues/2002-04/rhf/feature/index.php

 

[tankslave]

Yup, thats it! Thanks!

 

[Randy Holmes-Farley]

You're welcome

Happy Reefing.