kalk and mag

[spsgtr]

does limewater/kalk drop mag levels?

[boxfishpooalot]

QUOTE:
The primary sink for magnesium in aquaria is coprecipitation with calcium carbonate. This occurs in organisms, as shown in Table 1, and also during the abiotic (non-biologically driven) precipitation of calcium carbonate (such as on heaters).

A potential sink that has been described by some hobbyists is the precipitation of magnesium by limewater (kalkwasser). Both magnesium hydroxide and magnesium carbonate have been suggested. I do not believe that either is an important process in most aquaria. Adding any high pH additive, including limewater, results in the transient formation of magnesium hydroxide. This material quickly redissolves on mixing such that the local pH drops below about 8.6.-9.0. Magnesium carbonate is a more complicated issue, as it is near its solubility limit in seawater and may quickly get coated with a less soluble magnesium calcite. These issues have been dealt with by Bingman20 in much greater detail, and his conclusion is that neither of these precipitates is a likely sink for magnesium.




The water from lime does not lower magnesium. But heaters may do so.
http://www.advancedaquarist.com/issues/oct2003/chem.htm

[Randy Holmes-Farley]

In short, it doesn't lower magnesium, but it also doesn't add any, and the deposition of CaCO3 ends up using a bit, so magnesium may decline over time using limewater alone.

[spsgtr]

thanks.

[Randy Holmes-Farley]

:thumbsup:

Happy reefing. :)