Hello;
If you add Kalk too fast it creates Calcium Carbonate --- what most people see on their heaters first. This wastes your Kalk as Calcium Carbonate is not very solutable at reef tank PH. A cleaning in vinegar works well and the vinegar does not harm anything so don't worry as it will break down and feed the bacteria and release an OH molecule which is what Kalk or Calcium Hydroxide does.
A drip dose is the best method and can be as simple as a 2-liter bottle with a hard airline tube attached with some silicon through the cap. I use a knife and cut a small slit half way up on the side of the bottle for air to enter as the fluid exits. Then I attach some air line tube and a plastic airline valve. I fill the bottle just below the slit and drip it in the tank over 20-minutes or so. I usually remove the top of my skimmer and drip it in there where there is a lot of air entering so I get maximum mix and CO2.
From Reef Central -- Randy Holmes-Farley.
When carbon dioxide is dissolved in water, it hydrates to form carbonic acid:
15. CO2 + H2O à H2CO3
Then, if the pH is above 11, as it is in limewater, the carbonic acid equilibrates to form mostly carbonate:
16. H2CO3 + 2OH- à 2H2O + CO3--
It is the carbonate that we are concerned with in the degradation of limewater. It can combine with the calcium in limewater to form insoluble calcium carbonate:
17. Ca++ + CO3-- à CaCO3 (solid)
The result of this reaction is visually obvious. The calcium carbonate can be seen as a solid crust on the surface of limewater that has been exposed to the air for a day or two (do not bother to remove this crust, it may actually be protecting the underlying limewater from further penetration by carbon dioxide). The formed solids also settle to the bottom of the container (as described above). Since solid calcium carbonate is not an especially useful supplement of calcium or alkalinity, this reaction has the effect of reducing the limewater’s potency. With sufficient exposure to air, such as by aeration or vigorous agitation, this reaction can be driven to near completion, with little calcium or hydroxide remaining in solution.
The fact that limewater is very basic (the pH is typically above 12) demands that the limewater be added slowly to an aquarium unless very small additions are made. The reason for this is two-fold: to prevent the local pH in the area of the addition from rising too high (slow addition permits more rapid mixing with tank water to reduce the pH), and to prevent the overall tank pH from rising too high (slow addition allows the tank to pull in CO2 from the atmosphere during the slow addition, mitigating the pH rise). Some aquarists advocate rapid addition, and that is fine for small additions that would add less than 0.2 meq/L of alkalinity to the aquarium, but larger additions will drive the pH too high, as detailed below.
Full Article:
http://www.reefkeeping.com/issues/2005-01/rhf/index.php#6
I use 3-dkh of alk a day and about 60-ppm calcium. I do not have enough evaporation to add this amount with normal strength Kalk. I use 40-60 ml of white vinegar mixed with 3-times normal Kalk before adding water to mix in order to create a stronger mixture.
Enjoy!
OFM
