Jeff
Premium Member
Yes, I pulled this from an article written by randy. It specifically sites high ph from the addition of kalk:
One of the problems at higher pH (above 8.2, but getting progressively more problematic with each incremental rise) is the abiotic precipitation of calcium carbonate (resulting in a drop in calcium and alkalinity, and the clogging of heaters and pump impellers). If you are going to push the pH to 8.4 or higher (as often happens in a tank using limewater), make sure that both the calcium and alkalinity levels are suitably maintained (that is, neither too low, inhibiting biological calcification, nor too high, causing excessive abiotic precipitation on equipment).
And this:
When limewater is added to seawater, a cloudiness can form almost immediately . This initial cloudiness is magnesium hydroxide, Mg(OH)2, and it forms when the water's pH rises into the low to middle 10's. Theoretical and experimental reasons for believing this material to be Mg(OH)2 (and not magnesium carbonate or calcium carbonate, for example) are given later in this article. As the limewater is mixed in, the local pH around the particulates drops, and as soon as it drops below pH 10, the magnesium hydroxide dissolves.
If the limewater is not allowed to disperse rapidly enough, meaning that the pH does not drop fairly quickly, additional precipitates can form, especially calcium carbonate. Additionally, if the limewater drips onto surfaces in contact with seawater , bulk calcium carbonate can form on those surfaces. This precipitation takes place primarily because the limewater has pushed the CaCO3 supersaturation very high by converting much or all of the bicarbonate into carbonate. Since the precipitation of calcium carbonate can be slow to occur, rapid dispersal of the limewater doesn't lead to much or any precipitation of calcium carbonate. But if a region maintains high pH for long enough, calcium carbonate will precipitate. How long this process takes depends on the degree of supersaturation, but can be on the order of minutes to hours.
The entire article can be found here: http://www.reefkeeping.com/issues/2005-07/rhf/index.php#5
