Calcium Hydroxide / Lime Water / Kalkwasser

[tuan]

Purpose: Balanced Calcium and Alkalinity additive.
Sources: Branded from LFS, labpakchemicals, Builder's lime
Preparation:
- Mix well with fresh water, leave to settle and use the clear saturated solution.
- Use in Kalk stirrer/reactors
Usage:
- Slow drip into fast flowing area of tank or sump.


Additional readings:
Solving Calcium and Alkalinity Problems (http://www.advancedaquarist.com/issues/nov2002/chem.htm)
Calcium and Alkalinity Balance Issues (http://reefkeeping.com/issues/2002-04/rhf/feature/index.htm)
The Self Purification of Limewater (Kalkwasser) (http://www.advancedaquarist.com/issues/may2003/chem.htm)
The Degradation of Limewater (Kalkwasser) in Air (http://reefkeeping.com/issues/2003-05/rhf/feature/index.htm)

[simonh]

A saturated solution of limewater takes around 1.5grams per litre Ca(OH)2 at 25C rising to around 1.85grams per litre at 0C - depending on purity of the Ca(OH)2.

A saturated solution of limewater at normal temperatures will have a calcium level above 800ppm.

The strength of limewater can also be measured using conductivity (suchas a Pinpoint Salinity meter) where a saturated solution will have a conductivity of around 10mS/cm.

It is quite difficult to measure pH in limewater accurately especially with a pH probe calibrated at pH 7 and 10. pH of saturated limewater is also highly temperature dependent (@25C = pH 12.45, at 10C = pH 13.00). At 25C a saturated solution has a pH of 12.45, a pH of 12.15 would indicate a solution around half strength!